Improving functional outcome and outcome measures in total knee arthroplasty by wenz iD

Improving functional outcome and outcome measures in total knee arthroplasty

Bas Fransen

Improving functional outcome and outcome measures in total knee arthroplasty Bas Lennart Fransen

Improving functional outcome and outcome measures in total knee arthroplasty ÂŠ Bas L. Fransen, 2019 ISBN: 978-94-6380-554-4 Design and lay-out: Wendy Schoneveld || www.wenzid.nl Printed: ProefschiftMaken || Proefschiftmaken.nl This PhD thesis was embedded within Amsterdam Movement Sciences research institute, at the Department of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, the Netherlands in a joint effort with the Centre for Orthopaedic Research Alkmaar (CORAL) of the Department of Orthopaedic Surgery, Noordwest Ziekenhuisgroep Alkmaar, the Netherlands. Printing of this thesis was supported by: Nederlandse Orthopaedische Vereniging, Centre for Orthopaedic Research Alkmaar, Noordwest Academie part of Noordwest Ziekenhuisgroep, ORTHIS, Zimmer-Biomet, Mathys Orthopaedics BV, McRoberts, Oudshoorn chirurgische techniek, Smith+Nephew, Chipsoft.

VRIJE UNIVERSITEIT

Improving functional outcome and outcome measures in total knee arthroplasty

ACADEMISCH PROEFSCHRIFT ter verkrijging van de graad Doctor aan de Vrije Universiteit Amsterdam, op gezag van de rector magnificus prof.dr. V. Subramaniam, in het openbaar te verdedigen ten overstaan van de promotiecommissie van de Faculteit der Gedrags- en Bewegingswetenschappen op maandag 9 december 2019 om 13.45 uur in de aula van de universiteit, De Boelelaan 1105

door Bas Lennart Fransen geboren te Alphen aan den Rijn

promotor: prof.dr. J.H. van DieĂŤn copromotoren: dr. M.J.M. Hoozemans dr. B.J. Burger

CONTENTS CHAPTER 1

Introduction

PART 1 IMPROVING FUNCTIONAL OUTCOME CHAPTER 2

Fast-track total knee arthroplasty improves clinical and functional outcome in the first seven days after surgery. A randomized controlled pilot study with five years follow-up

CHAPTER 3

No differences between fixed- and mobile-bearing total knee arthroplasty

CHAPTER 4

Does insert type affect clinical and functional outcome in total knee arthroplasty? A randomised controlled clinical trial with 5-year follow-up

4.1

Letter to editor: Does insert type affect clinical and functional outcome in total knee arthroplasty? A randomised controlled clinical trial with 5-year follow-up

103

4.2

In reply: Does insert type affect clinical and functional outcome in total knee arthroplasty?

109

PART 2 IMPROVING FUNCTIONAL OUTCOME MEASURES CHAPTER 5

Cross-cultural adaptation and validation of the Dutch version of the High Activity Arthroplasty Score

117

CHAPTER 6

Gait quality assessed by trunk accelerometry after total knee arthroplasty and its association with patient related outcome measures

133

CHAPTER 7

Patientsâ&#x20AC;&#x2122; daily-life gait quality, gait behavior, and perceived 155 walking abilities before and 3 months after total knee arthroplasty

CONCLUDING REMARKS CHAPTER 8

Epilogue

175

CHAPTER 9

Nederlandstalige samenvatting

195

CHAPTER 10

Dankwoord

203

CHAPTER 11

Curriculum vitae

209

CHAPTER 12

Publication list

213

CHAPTER 1 Introduction

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Background Knee symptoms are very common. Over 1 in 5 persons experience a form of knee pain every year, with one-third of these persons visiting a doctor with their complaint.1 These complaints comprise a large spectrum of maladies including sports injuries, trauma, infectious diseases, and degenerative diseases. One of the most common causes of knee symptoms, especially in older adults, is osteoarthritis (OA) of the knee. Pain free and sufficient movement of the knee is largely dependent on the existence of healthy hyaline cartilage on the articulating surfaces of the femur, tibia and patella. Knee OA is a disease in which the cartilage of the knee progressively deteriorates, resulting in pain, impairment in performing daily activities, and worsening of quality and quantity of gait. Total knee arthroplasty (TKA), in which an artificial joint replaces the affected cartilage and bone, has been successfully used for decades to improve the life of patients suffering of knee OA. Unfortunately, there remain a significant percentage of patients who are unsatisfied or experience residual pain and/or functional impairments after TKA surgery. In this thesis, I present studies on several ways to improve functional outcome and functional outcome measures after TKA. Osteoarthritis of the knee Patients suffering from OA in the knee experience (nightly) pain, stiffness and decreased mobility. This can result in high morbidity and loss of quality of life (QoL), with worse grades of OA resulting in further deterioration of QoL.2 OA of the knee can have large consequences for a patientâ&#x20AC;&#x2122;s ability to work, participate in sports, and partake in daily social activities.3 Data from the Global Burden of Disease study in 2010 showed that hip and knee OA were ranked number 11 in the list of diseases contributing to global disability, with an average of 10 years of life with disability per patient.4 Although exact global data for osteoarthritis have not been calculated since, the numbers appear to be increasing further when calculated regionally.5 Approximately 47.400 new cases of knee OA were registered in the Netherlands in 2017, which makes it the most frequently diagnosed type of OA and means that of every 1000 persons about 3 receive the diagnosis per year.6 When looking at all knee OA patients, the percentage of women is notably higher (63%) compared to men (31%). Prevalence of knee OA increases with higher age to 33.6% among individuals over 65 years of age.7 The chance of developing knee OA appears to be influenced by a number of factors. A higher body mass index (BMI), female gender, and traumatic injuries to the cartilage are known to increase the risk of developing OA in the knee.8,9 X-rays by themselves are insufficient for the diagnosis of knee OA, since there is a

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discrepancy between the stage of OA on the X-ray and the severity of the symptoms experienced by the patients.10 Therefore, diagnosis of knee OA is made by combining the history of pain and disability experienced by patients, physical examination, and severity of OA on an X-ray of the knee. Changes in knee kinematics and gait in patients with osteoarthritis of the knee The knee is often described as a tri-compartmental joint with a medial tibiofemoral, lateral tibiofemoral and the patellofemoral compartment. Although the knee used to be thought of as a hinge-type joint with flexion and extension, during motion there is also rotation of the tibia in the transverse plane.11 When the knee is flexed, the medial femoral condyle barely moves relative to the tibial articular surface, whereas the lateral condyle translates posteriorly moving the tibio-femoral contact point and allowing full flexion. This movement, called femoral rollback, is possible because of internal rotation of the tibia.11 Knee OA causes several changes in knee kinematics and affects gait characteristics of patients. Femoral rollback12, flexion/extension12 and spatiotemporal parameters (e.g. gait speed, single-leg stance time, cadence) are frequently changed in the gait pattern of knee OA patients when compared to healthy controls, as Movin et al. showed in patients with medial compartment OA.13 Patients with severe knee OA walk slower compared to healthy people, with an increase in stride duration and a reduced cadence.14 This reduction in gait speed is predictive of disability15, depressive symptoms16, and mortality17, and is therefore an important reflection of the reduced QoL of knee OA patients. Gait speed in knee OA patients is further reduced by associated factors like age, self-efficacy and opioid use.18 Treatment of knee osteoarthritis When patients are first diagnosed with OA of the knee, they generally start with conservative treatment aimed at relieving OA symptoms. A stepped care approach consisting of painkillers (usually non-steroidal anti-inflammatory drugs (NSAIDs)), shoe inlays, muscle strength exercises and intra-articular injections with corticosteroids can give (temporary) relief and allow patients to function satisfactorily for a longer period of time. Additionally, specialized programs in which orthopaedic surgeons work together with physical therapists both before and after TKA surgery can improve muscle strength postoperatively.19 When nonoperative treatment fails, surgical options can be considered. In relatively young patients with a significant varus or valgus alignment of the knee, it is possible to

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perform proximal tibial osteotomies or distal femoral osteotomies respectively to normalize the alignment.20 This can unload the medial compartment (in varus OA), or the lateral compartment (in valgus OA), which reduces symptoms and postpones an (partial) arthroplasty. Uni-compartmental knee OA can be treated by replacing the affected compartment with a medial, lateral, or patellofemoral uni-compartmental knee prosthesis. However, worldwide the most performed and most extensively researched surgical treatment of knee OA is the TKA.21 Which treatment is most suited for a specific patient is often debatable, and it is important to inform patients about the benefits and risks of each specific type of treatment. This allows patients to decide together with their treating physician if surgery and which type of surgery would be the best option. Total knee arthroplasty and outcome TKA has extensively been used to treat end-stage OA of the knee for the last half century. During TKA surgery, the destructed bone and cartilage surface is removed and replaced with a metal femoral and tibial component with a polyethylene (PE) insert in between. If necessary, the articular surface of the patella can also be replaced with an inlay or onlay patella component. With TKA, most patients experience significant pain reduction and regain knee function.22 Ruiz et al. calculated that in the United States, TKA is responsible for an annual saving of 12 billion U.S. dollars, mostly due to patients being able to return to work.23 Over 27.000 total knee replacements were performed in the Netherlands in 2017, and the number is expected to rise further in the coming years.24 This expected increase is largely attributed to the increase in obesity worldwide, combined with a more active and more demanding patient population. Unlike patients who undergo total hip arthroplasty, a significant proportion of TKA patients are unsatisfied with the end result of the procedure. It is estimated that 10-20% of patients continue to experience a varying amount of pain, limited function, stiffness and/or hindrance in daily activities.25,26 These numbers tend to remain similar with increasing time after surgery.27 Even higher dissatisfaction rates have been reported in younger patients: Scott et al. showed that in a group of TKA patients younger than 55 years old, 24.9% was dissatisfied with the endresult.28 Since increasing numbers of younger patients undergo TKA, and patients desire to remain active or participate in sports to an older age29, the need for improvement of postoperative results and function of TKA patients has increased as well. A number of factors have been identified that may contribute to reduced patient satisfaction: limited OA on the preoperative X-ray of the knee (especially in young

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active patients),28 unrealistic patient expectations before surgery,30 comorbidities like depression and diabetes,31 and worse preoperative pain scores.27 These factors can only explain part of the relatively large proportion of unsatisfied TKA patients. Understandably, orthopaedic research worldwide has been increasingly trying to understand which patient groups are more likely to be unsatisfied, why they are unsatisfied, and has tried to improve outcome. More and more attention of researchers is focused on trying to understand functional outcome and on finding better ways of measuring functional outcome in TKA patients.

IMPROVING FUNCTIONAL OUTCOME Numerous studies have reported attempts to improve functional outcome after TKA. Two approaches have been widely adapted and have, therefore, been studied extensively: fast-track protocols, where multiple perioperative adjustments are combined to allow patients to start mobilization and rehabilitation quickly, and advances in prosthesis designs, most notably the development of mobile bearing inserts, aimed at reproducing natural knee kinematics as accurately as possible. Fast-track protocols Until the turn of the century, patients remained in hospital for an average of 10-14 days after TKA. Patients would start mobilisation slowly, often remaining in bed for the first couple of days after surgery. With increasing numbers of patients undergoing TKA and rising healthcare costs, many initiatives were started to reduce the length of stay (LOS) without increasing complications or reducing patient satisfaction. Hospitals started combining these initiatives into so-called fast-track protocols. The early fast-track protocols, e.g. the Joint Care protocol, aimed at mobilising patients earlier and resulted in LOS being reduced to 5-7 days.32 These protocols combined changes of several aspects of TKA surgery, including anesthesia techniques, the use of tourniquets, catheters and drains, reduction of opioid use, and type and start of rehabilitation. Especially pain reduction appears to be one of the most important factors in the success of fasttrack protocols.33 Since these early protocols, further modifications have reduced LOS to as short as 2-3 days.34 Most studies found that, when the protocol is executed correctly, these reductions are not associated with higher rates of readmission, complications, or revision surgery.34,35 It has been shown that also in older patients, unlike one might expect, fast-track protocols are feasible and show

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similar improvements in LOS reduction without a negative effect on outcome.36 A retrospective database study by Sutton et al. showed indications that further LOS reduction to discharge within two days after surgery could be safe.37 With the known challenges in achieving satisfactory functional outcome after TKA, this raises the question whether discharge from hospital within 2 days after surgery can be achieved without a reduction in (long-term) functional outcome. Implant design Because the design of TKA implants influences outcome in TKA patients38, orthopaedic surgeons, researchers and manufacturers are continuously trying to innovate the design of the implants and materials used. One of the most widely used changes to TKA design is the development of the mobile bearing TKA (MBTKA) in the late 1970s. Until then, the PE insert was fixed in place on the tibial metal component. This is called fixed bearing TKA (FB-TKA). In FB-TKA, the primary range of motion of the prosthesis is flexion and extension, with the only rotation derived from the femoral componentsâ&#x20AC;&#x2122; ability to rotate on the insert. In MB-TKA, the PE insert can move to some degree in one or more directions (e.g. rotation, anterior-posterior translation) relative to the tibial component. The rationale behind this is that by allowing increased motion in the prosthesis, the movement of the TKA during walking more accurately mimics the natural motion of the healthy knee. Although plenty of research has been performed comparing MB-TKA and FB-TKA, few have been able to detect differences between the two designs. The most recent Cochrane review into this topic showed that the research that has been performed, has mostly been of moderate to low quality.39 This makes it difficult to formulate firm conclusions on which type of bearing would be favored. There is therefore a need for randomised trials between MB-TKA and FB-TKA with adequate follow-up. Furthermore, since large numbers of studies into this subject would be disregarded in systematic reviews or meta-analyses because of their methodological setup, it might be interesting to determine whether a closer look on the broader body of literature on MB-TKA and FB-TKA gives new insights into which type of bearing is preferable.

IMPROVING FUNCTIONAL OUTCOME MEASURES Another large part of TKA research focuses on trying to improve the methods of measuring (functional) outcome. The rationale behind this is that with increased understanding of how patients function after TKA, it is possible to find new

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approaches for increasing satisfaction levels and patientsâ&#x20AC;&#x2122; function after TKA. Research into functional outcome measures concentrates both on subjective measurements like patient reported outcome measures (PROMs), which have already been extensively used in TKA studies, as well as on objective measurements in the form of in-depth gait analyses, which are widely used in human movement sciences but are relatively novel in TKA research. Patient reported outcome measures PROMs is the general term used for a variety of self-reported questionnaires which allow researchers to quantify a wide selection of outcome variables like pain, satisfaction, QoL, and function. They are designed to be easy-to-use, practical tools to allow physicians and researchers to quickly obtain data from patients. They are almost ubiquitous in TKA research and are even mandatory tools to evaluate quality of care in Dutch hospitals. However, the most often used PROMs (e.g. the Knee Society Score and the Knee injury and Osteoarthritis Outcome Score) were developed several decades ago and recent research has suggested that there are methodological limitations to the use of these questionnaires.40,41 An issue with PROMs that has been become more apparent recently, is a problem with ceiling effects. This means that a large proportion of patients filling in the questionnaire obtain the highest possible score, which results in the test being unable to sufficiently discriminate between patients. One of the reasons for the fact that more ceiling effects are reported is that a growing proportion of patients is relatively young (below 55-60 years of age).42 These patients are more active and are often involved in heavy physical work or intensive sports participation after undergoing TKA surgery.43,44 Therefore, there is an increasing need for PROMs that are able to discriminate between TKA patients that perform daily activities on a high or very high level. Gait analysis Focusing on functional outcome has become increasingly relevant, because of the aforementioned changes in the population of patients with a TKA. As described above, PROMs have several limitations in their psychometric properties and appear to be unable to fully assess functional outcome after TKA. Recently, there are increasing indications that objective measurements like gait analysis could be an addition to PROMs in the evaluation of TKA results.45 This makes sense, since knee OA has been shown to significantly impair gait. Furthermore, PROMs are mostly associated with pain, and there are indications that pain in itself is not associated with the decrease in walking speed and quality of gait

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found in end-stage knee OA patients.46 Therefore, simple gait analysis techniques (e.g. step times, knee flexion angles) have been used more and more in the evaluation of TKA patients. Unfortunately, the term “gait analysis” (similar to the terms “function” or “functional outcome”) has been used to describe a myriad of tests. These vary from simple tests like the Timed-Up and Go test in which patients stand up from a chair and start walking with time to execute the task as outcome, to 3-dimensional video analyses of gait on computer-guided treadmills with detailed kinematic and kinetic data as outcome. The need for objective measurement of functional TKA outcome has led researchers to use more detailed gait analysis as used in the field of human movement sciences with, for example, devices like Inertial Measurement Units (IMUs), generally including 3D accelerometers, gyroscopes, and magnetometers. So far, these have not been extensively used in the field of orthopaedic surgery. With IMUs becoming smaller, more accessible and more practical with longer battery lives, the use of these devices in orthopaedic research has become more feasible. Accelerometers measure acceleration in three dimensions and can be used to accurately measure the quality of gait.47 Accelerometers have already been used in analysing TKA outcome, but in differing ways. Unfortunately, this makes it difficult to compare outcomes between studies. They have been used to measure knee angles by attaching accelerometers on the upper and lower leg48, to analyse the amount and intensity of activity with a trunk-based uniaxial accelerometer49, and to analyse the number of steps and activity levels by attaching an accelerometer to the unaffected upper leg.50 Using accelerometers in measuring outcome can be challenging, as shown by the study of Kluge et al., who looked at spatiotemporal gait variables using a foot worn accelerometer in a small group of 24 patients, of whom 25% declined to participate for follow-up measurements.51 Within the field of human movement sciences, gait analysis with tri-axial trunk based accelerometers is successfully used to achieve a complete analysis of the quality of gait in older adults47, patients after a stroke52 and older adults with a risk of falling53. The use of this form of accelerometry allows researchers to not only analyse spatiotemporal parameters like stride times, step lengths, or walking speed, but to combine these with parameters that quantify gait symmetry and smoothness (e.g. harmonic ratio54 and index of harmonicity55) and gait stability or variability (e.g. low frequency percentage47). Analysing gait quality with trunkbased tri-axial accelerometers has not yet been performed before and/or after TKA, and could provide a better understanding of functional (gait-related) outcome or new insights for improving rehabilitation in TKA patients.

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AIM AND OUTLINE OF THIS THESIS The general aim of this thesis is to analyse different innovations aimed at improving functional outcome and improving functional outcome measures in total knee arthroplasty.

PART 1 Improving functional outcome Fast-track protocols There have been indications that hospital discharge within two days after TKA surgery using a fast-track protocol is feasible, but randomised trials analyzing both clinical and functional outcome of such a protocol are scarce. In Chapter 2, we performed a randomised clinical trial (RCT) comparing the regularly used protocol for TKA patients to the 2 Day Knee (2DK) protocol, which is a fast-track protocol specifically designed to allow patients to be discharged 2 days after surgery whilst maintaining high satisfaction levels and without increasing complication rates. We put special emphasis on the short-term results in the first 7 days after surgery. Implant design Most reviews and meta-analysis of studies comparing MB-TKA and FB-TKA only include the same small number of high-quality RCTs. Therefore, in Chapter 3 an extensive overview of the literature is presented, which incorporated important other types of research (e.g. implant removal studies) on MB-TKA and FB-TKA, to determine whether combining all this research could provide further indications on differences in insert wear, signs of loosening, survival rate of the prosthesis, and clinical outcome between the two types of TKA bearing. Over the last couple of years, both MB-TKA and FB-TKA have been developed further and adjustments have been made to the PE inserts. This has resulted in several different types of inserts now being available to use in TKA surgery. To determine whether different types of MB-TKA and FB-TKA PE inserts could influence outcome, in Chapter 4 a randomised clinical trial is presented comparing four types of inserts, two versions of MB-TKA and two versions of FB-TKA. Both clinical outcome and functional outcome using gait analysis were determined for the individual inserts and for FB-TKA and MB-TKA combined.

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PART 2 Improving functional outcome measures Patient reported outcome measures The High Activity Arthroplasty Score (HAAS) is a relatively new questionnaire developed to address the ceiling effect found in high demanding and active patients in other PROMs. In Chapter 5, a cross-cultural adaptation was done, and the Dutch version of the HAAS was validated in TKA and THA patients. Gait analysis There are no feasibility studies determining whether trunk-based tri-axial accelerometers could be used in analyzing gait and functional outcome after TKA patients. In this thesis, two different patient cohorts are analysed. First, in Chapter 6, patients undergoing TKA were measured with an accelerometer before and 1 year after surgery. This involved patients walking 2x 50 meters each time, and completing PROMs that were then correlated with the gait parameters. This was done to assess what quality of gait patients could achieve in optimally controlled conditions one year after TKA, and to determine whether this form of functional analysis could be an addition to PROMs. As a follow-up study, a second cohort of TKA patients was asked to wear an accelerometer for a whole week during their daily activities, both before and 3 months after TKA. The results reported in Chapter 7 describe the analysis of patientsâ&#x20AC;&#x2122; gait quality, gait behavior (measured with walking speed and quantity of gait), and their cognition about their own walking abilities as measured with questionnaires. This was done to provide insight in how patients function in a domestic environment, and to see whether their behaviour at home and cognition about their abilities corresponded with their actual behavior and quality of gait.

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22. Van Egmond JC, Verburg H, Mathijssen NMC. The first 6 weeks of recovery after total knee arthroplasty with fast track. Acta Orthop. 2015;86:708–13 23. Ruiz D, Koenig L, Dall TM, Gallo P, Narzikul A, Parvizi J, et al. The direct and indirect costs to society of treatment for end-stage knee osteoarthritis. J Bone Joint Surg Am. 2013;95:1473–80 24. Dutch Arthroplasty Register (LROI). Online LROI annual report 2017: 10 years of registration, a wealth of information. 2017 25. Robertsson O, Dunbar M, Pehrsson T, Knutson K, Lidgren L. Patient satisfaction after knee arthroplasty: a report on 27,372 knees operated on between 1981 and 1995 in Sweden. Acta Orthop Scand. 2000;71:262–7 26. Bourne RB, Chesworth BM, Davis AM, Mahomed NN, Charron KDJ. Patient satisfaction after total knee arthroplasty: who is satisfied and who is not? Clin Orthop Relat Res. 2010;468:57–63 27. Clement ND, Bardgett M, Weir D, Holland J, Gerrand C, Deehan DJ. Three groups of dissatisfied patients exist after total knee arthroplasty: early, persistent, and late. Bone Joint J. 2018;100B:161–9 28. Scott CEH, Oliver WM, MacDonald D, Wade FA, Moran M, Breusch SJ. Predicting dissatisfaction following total knee arthroplasty in patients under 55 years of age. Bone Joint J. 2016;98B:1625–34 29. Hepperger C, Gföller P, Abermann E, Hoser C, Ulmer H, Herbst E, et al. Sports activity is maintained or increased following total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2018;26:1515–23 30. Neuprez A, Delcour J-P, Fatemi F, Gillet P, Crielaard J-M, Bruyère O, et al. Patients’ Expectations Impact Their Satisfaction following Total Hip or Knee Arthroplasty. Nazarian A. PLoS One. 2016;11:e0167911 31. Clement ND, Bardgett M, Weir D, Holland J, Gerrand C, Deehan DJ. The rate and predictors of patient satisfaction after total knee arthroplasty are influenced by the focus of the question. Bone Joint J. 2018;100-B:740–8 32. den Hertog A, Gliesche K, Timm J, Mühlbauer B, Zebrowski S. Pathway-controlled fast-track rehabilitation after total knee arthroplasty: a randomized prospective clinical study evaluating the recovery pattern, drug consumption, and length of stay. Arch Orthop Trauma Surg. 2012;132:1153–63 33. Holm B, Kristensen MT, Myhrmann L, Husted H, Andersen LØ, Kristensen B, et al. The role of pain for early rehabilitation in fast track total knee arthroplasty. Disabil Rehabil. 2010;32:300–6 34. Pamilo KJ, Torkki P, Peltola M, Pesola M, Remes V, Paloneva J. Fast-tracking for total knee replacement reduces use of institutional care without compromising quality. Acta Orthop. 2018;89:184–9 35. Husted H, Otte KS, Kristensen BB, Orsnes T, Kehlet H. Readmissions after fast-track hip and knee arthroplasty. Arch Orthop Trauma Surg. 2010;130:1185–91 36. Pitter FT, Jørgensen CC, Lindberg-Larsen M, Kehlet H, Lundbeck Foundation Center for Fast-track Hip and Knee Replacement Collaborative Group. Postoperative Morbidity and Discharge Destinations After Fast-Track Hip and Knee Arthroplasty in Patients Older Than 85 Years. Anesth Analg. 2016;122:1807–15 37. Sutton JC, Antoniou J, Epure LM, Huk OL, Zukor DJ, Bergeron SG. Hospital Discharge within 2 Days Following Total Hip or Knee Arthroplasty Does Not Increase Major-Complication and Readmission Rates. J Bone Joint Surg Am. 2016;98:1419–28 38. Hamilton DF, Burnett R, Patton JT, Howie CR, Moran M, Simpson AHRW, et al. Implant design influences patient outcome after total knee arthroplasty: a prospective double-blind randomised controlled trial. Bone Joint J. 2015;97-B:64–70 39. Hofstede SN, Nouta KA, Jacobs W, van Hooff ML, Wymenga AB, Pijls BG, et al. Mobile bearing vs fixed bearing prostheses for posterior cruciate retaining total knee arthroplasty for postoperative functional status in patients with osteoarthritis and rheumatoid arthritis. Cochrane database Syst Rev. 2015;CD003130 40. Hossain FS, Konan S, Patel S, Rodriguez-Merchan EC, Haddad FS. The assessment of outcome after total knee arthroplasty. Bone Joint J. 2015;97-B:3–9

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41. Ramkumar PN, Harris JD, Noble PC. Patient-reported outcome measures after total knee arthroplasty: a systematic review. Bone Joint Res. 2015;4:120–7 42. Talbot S, Hooper G, Stokes A, Zordan R. Use of a new high-activity arthroplasty score to assess function of young patients with total hip or knee arthroplasty. J Arthroplasty. 2010;25:268–73 43. Kuijer PPFM, Kievit AJ, Pahlplatz TMJ, Hooiveld T, Hoozemans MJM, Blankevoort L, et al. Which patients do not return to work after total knee arthroplasty? Rheumatol Int. 2016;36:1249–54 44. Kievit AJ, van Geenen RCI, Kuijer PPFM, Pahlplatz TMJ, Blankevoort L, Schafroth MU. Total Knee Arthroplasty and the Unforeseen Impact on Return to Work: A Cross-Sectional Multicenter Survey. J Arthroplasty. 2014;29:1163–8 45. Luna IE, Kehlet H, Peterson B, Wede HR, Hoevsgaard SJ, Aasvang EK. Early patient-reported outcomes versus objective function after total hip and knee arthroplasty: a prospective cohort study. Bone Joint J. 2017;99-B:1167–75 46. Thomas SG, Pagura SMC, Kennedy D. Physical activity and its relationship to physical performance in patients with end stage knee osteoarthritis. J Orthop Sports Phys Ther. 2003;33:745–54 47. Rispens SM, Pijnappels M, van Schooten KS, Beek PJ, Daffertshofer A, van Dieën JH. Consistency of gait characteristics as determined from acceleration data collected at different trunk locations. Gait Posture. 2014;40:187–92 48. Rahman J, Tang Q, Monda M, Miles J, McCarthy I. Gait assessment as a functional outcome measure in total knee arthroplasty: a cross-sectional study. BMC Musculoskelet Disord. 2015;16:66 49. Kahn TL, Schwarzkopf R. Does Total Knee Arthroplasty Affect Physical Activity Levels? Data from the Osteoarthritis Initiative. J Arthroplasty. 2015;30:1521–5 50. Schotanus MGM, Bemelmans YFL, Grimm B, Heyligers IC, Kort NP. Physical activity after outpatient surgery and enhanced recovery for total knee arthroplasty. Knee Surgery, Sport Traumatol Arthrosc. 2017;25:3366–71 51. Kluge F, Hannink J, Pasluosta C, Klucken J, Gaßner H, Gelse K, et al. Pre-operative sensor-based gait parameters predict functional outcome after total knee arthroplasty. Gait Posture. 2018;66:194–200 52. Punt M, Bruijn SM, van Schooten KS, Pijnappels M, van de Port IG, Wittink H, et al. Characteristics of daily life gait in fall and non fall-prone stroke survivors and controls. J Neuroeng Rehabil. 2016;13:67 53. van Schooten KS, Pijnappels M, Rispens SM, Elders PJM, Lips P, van Dieën JH. Ambulatory fallrisk assessment: amount and quality of daily-life gait predict falls in older adults. J Gerontol A Biol Sci Med Sci. 2015;70:608–15 54. Menz HB, Lord SR, Fitzpatrick RC. Acceleration patterns of the head and pelvis when walking on level and irregular surfaces. Gait Posture. 2003;18:35–46 55. Lamoth CJC, Beek PJ, Meijer OG. Pelvis-thorax coordination in the transverse plane during gait. Gait Posture. 2002;16:101–14

PART 1 Improving functional outcome

CHAPTER 2 Fast-track total knee arthroplasty improved clinical and functional outcome in the first seven days after surgery: a randomized controlled pilot study with five-year follow-up

Archives of Orthopaedic and Trauma Surgery. 2018 Sep;138(9):1305-1316. BL Fransen, MJM Hoozemans, KD Argelo, LCM Keijser, BJ Burger

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ABSTRACT Introduction Fast-track protocols (FP) are used more and more to optimize results after total knee arthroplasty (TKA). Many studies evaluating FP in TKA concentrate on clinical outcome and medium to long-term results. Since discharge from hospital after TKA is achieved increasingly quicker worldwide using FP in an increasingly younger and active patient population, the effects of FP on functional outcome in the first days after TKA become more important. The purpose of the current study was to compare FP with a regular joint care protocol (RP), with an emphasis on the first seven days after surgery. Materials and Methods A non-blinded randomized controlled clinical pilot study was performed with 25 patients assigned to a FP group and 25 patients assigned to a RP group. Primary outcome was functional outcome, clinical outcome, pain, and complications for each day in the first week after surgery. Patients were followed up to five years after surgery. Results Significantly lower VAS scores for knee pain, faster Timed-Up and Go test times and more mobility on functional tests were seen on several days in the first week in the FP group compared to the RP group. Few other significant differences were found at two, six weeks, and no significant differences were found at 12 weeks and 1, 2 and 5 years after surgery. Conclusions Fast-track protocol for primary TKA showed significantly lower knee pain scores and improved functional outcome in the first seven days after TKA compared to a regular protocol.

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

INTRODUCTION Total knee arthroplasty (TKA) has been performed since the 1960s and has significantly improved the quality of life of patients suffering from osteoarthritis of the knee1, 2. Recent trends show that patients undergo surgery at a younger age3, 4. Furthermore, they want to be able to return to their daily activities and work as soon as possible3. To accommodate these trends and to further optimize outcome in TKA patients, patient care is continuously being improved throughout the patientâ&#x20AC;&#x2122;s hospital admission. Due to multimodal analgesia, and improvements in wound care, physical therapy, operative techniques and hospital logistics, length of stay (LOS) has decreased to such an extent that 75% of patients remain in hospital for 3 days or less after TKA. A combination of these measures has increasingly been used in fast-track protocols5. The first fast-track protocols reduced LOS from an average of two weeks to less than one week6. Since then fast-track protocols for TKA have been shown to reduce LOS even further, to maintain patient satisfaction without increasing the number of complications or readmissions5, 7â&#x20AC;&#x201C;10, to reduce morbidity and mortality, to increase cost-effectiveness11, and to be feasible in all age groups12, 13. These studies show that a fast-track protocol leads to similar results in the mid- to long-term follow-up compared to regular protocols. To fully understand the effects of fast-track TKA, studies should also focus on the short-term outcome. A few studies have described short-term results of fast-track TKA and reported good outcomes with respect to pain reduction7, 14 and the Timed Up and Go (TUG) test15 in the first days after surgery. Unfortunately, these results were not compared to a non-fast-track control group. Therefore, the main goal of the present pilot randomized clinical trial was to evaluate whether our fast-track TKA protocol (called the 2 Day Knee (2DK) protocol) resulted in better outcome than a regular protocol in patients who underwent primary TKA, with an emphasis on the daily clinical and functional outcomes in the first week after surgery. The secondary goal was to compare outcomes between both treatment protocols up to 5 years after surgery.

MATERIALS AND METHODS Study Design A feasibility pilot study was done to provide early indications whether the possible benefits of the 2DK protocol in the first week after surgery were sufficient to justify

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a long-term study with a larger patient population. A single centre, non-blinded, randomised controlled clinical trial (RCT) was performed. After inclusion and providing informed consent, patients were randomly assigned to either the regular joint care protocol (RP) or the 2DK fast-track protocol (FP), which is used in our hospital, with an allocation ratio of 1:1, after which the baseline measurements were performed. All procedures were in accordance with the Declaration of Helsinki16, the CONSORT guidelines17, and Good Clinical Practice guidelines18. A Medical Ethical Committee gave approval for this study under number NL33089.094.10. The study protocol was registered in the International Standard Randomised Controlled Trial Number Register with number ISRCTN51839535. When 20 patients had been treated, an interim analysis was performed which showed no contra-indication for continuing the study. After 2 years the decision was made not to perform a larger scale study since most measures from the protocol had already been implemented in daily practice. However, patients were asked to fill in the questionnaires one additional time 5 years after surgery to determine whether the differences found in the first week had effects on mid-term outcome. Study Population Patients were eligible for inclusion if they required a primary unilateral TKA, had American Society of Anaesthesiologists (ASA) status I or II, and were willing and able to comply with the scheduled postoperative clinical and radiographic evaluations and with the rehabilitation program. Patients were excluded if they had other lower limb problems or were diagnosed with insulin dependent diabetes, severe osteoporosis, rheumatoid arthritis, or a different inflammatory cause for osteoarthritis. Intervention and control protocols All patients in both groups received Scorpio cruciate-retaining total knee prostheses (Stryker, Mahwah, U.S.A.). Premedication consisted of paracetamol 1000 milligrams and temazepam 10 milligrams. All surgeries were performed by one of two experienced orthopaedic surgeons, each of whom operated patients in both groups. The physical therapy protocol was identical for both groups. Patients were discharged if they were able to ambulate independently â&#x20AC;&#x201C; either with two crutches or a walker â&#x20AC;&#x201C; and if there were no wound problems. Patients who did not have a good domestic support network, or who did not mobilize adequately according to the physical therapist were referred to a rehabilitation facility. Here they continued training until they were able to return home, which

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

was usually achieved within 1-2 weeks. Trombo-embolic prophylaxis was fraxiparine 2850 international units once a day for 4 weeks. No steroids were given as part of the protocols. There were no differences between the two groups in the preoperative preparation of patients. Fast-track protocol In the fast-track protocol (FP), no tourniquet was used during the operation. Omitting the tourniquet was assumed to reduce pain, bleeding and swelling after surgery, thereby leading to a possible faster activation of muscle function and performance. The operation was performed through a subvastus approach, a patella-in-place balancer was used, and patients received intra-operative local infiltration analgesia (LIA)19. All patients received a patella component. The risk for infection was minimized by not using pain pumps, wound drains or bladder catheters. The post-operative protocol focused on rapid mobilization under guidance of a physiotherapist. Postoperatively patients received paracetamol 1000 milligrams four times a day, diclofenac 50 milligrams three times a day (unless they had an allergy for non-steroidical anti-inflammatory drugs) and oral oxynorm 5 mg only when needed. Patients in the FP were told to expect being discharged from the hospital 2 days after surgery. Regular protocol The regular protocol (RP) group underwent the regular hospital TKA protocol, which included the use of a tourniquet, wound drains and bladder catheter. The operation was performed through a midline approach. All patients received a patella component. Mobilization was started the first day after surgery, and patients were told beforehand that the average discharge was 4 days after surgery. Similar to the FP, postoperatively patients received identical doses of paracetamol and diclofenac. Contrary to the FP group, patients started with a patient-controlled analgesia (PCA) pump with intravenous morphine. Patients in both groups reduced opioid use as soon as pain allowed this. All differences between the two protocols are shown in Table 1. First week measurements Patients were requested to keep a daily diary for the first week after surgery. While in the hospital, the patients were assisted by a nurse and were instructed in how to complete the diary on a daily basis at home. The outcome measures included were the visual analogue scale (VAS) scores for knee pain and the Timed Up and Go test (TUG)20 scores. The VAS scores ranged from 0 (best) to 100 (worst), and

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Table 1. Differences between RP (regular protocol) and FP (fast-track protocol) Regular protocol (RP) Spinal anaesthesia if possible Medial parapatellar approach No patella in-place balancing Soft tissue releases if required Tourniquet Patient Controlled Analgesia (PCA) with iv morfine, wound drains and bladder catheter No local infiltration analgesia (LIA) No ice packs Special chair to elevate leg and to get out of chair Joint loading one day after surgery Standard short-acting opiates

Fast-track protocol (FP) General anaesthesia Subvastus approach Patella in-place balancing No or limited soft tissue releases No tourniquet No pain pumps, wound drains or bladder catheter LIA intra-operatively Use of ice packs (3x3 times per day) No special chairs Immediate loading of the joint Short acting opiates only when requested

were measured both with the patient resting in bed as well as during movement with weight bearing on the knee. VAS scores in rest were also obtained immediately after surgery in the recovery room, and at 1 and 2 hours after surgery. The TUG scores were measured in seconds, a lower score indicating better function. Furthermore, patients were asked to report daily for the first seven days after surgery whether they were able to perform a straight leg raise, stand on their affected leg for 5 seconds, walk the stairs independently and/or were able to stand up from a sitting position. Short-term and mid-term outcomes To evaluate short-term outcomes, patients were asked to return to the outpatient clinic at 2, 6 and 12 weeks postoperatively. At these visits, function was assessed using the TUG test (at 2 and 6 weeks postoperatively only) and by assessing the knee range of motion (ROM) measured with a goniometer. Maximum flexion and extension were examined both actively and passively, and extension lag was described with a negative value, while hyperextension was described with a positive value. Clinical outcome was assessed with the VAS knee pain score (both at rest and during movement), the Short Form 12 (SF-12), and the Knee injury and Osteoarthritis Outcome Score (KOOS). The KOOS21 measures outcome in five subscores, ranging between 0 (worst) and 100 (best). The SF-12 health survey22 was used to measure quality of life (QoL) in mental and physical subscores, with higher scores indicating a higher QoL. To assess mid-term clinical outcome,

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

patients were asked to complete the KOOS and SF-12 at 1, 2 and 5 years followup. After the 5-year interval, the VAS knee pain score was included in the followup measurements. Complications All complications were registered for each group. At each follow-up measurement, the researcher assessed whether a complication had occurred. Sample size Since this was a pilot study, no sample size calculation was performed. In each group 25 patients were included, which was deemed sufficient to provide an indication about the early results of the fast-track protocol. Randomisation and blinding An independent researcher randomly allocated a protocol (25 RP and 25 FP) to study numbers 1 through 50, and the allocation was concealed in sealed envelopes. After a patient was included and a study number was assigned, a research assistant opened the envelope. Patients were told their allocation before surgery, since it was impossible to keep the patients blinded because of the different incisions and rehabilitation protocols. Statistical analysis Independent t-tests or their non-parametric equivalent were performed on all patient characteristics and baseline measurements for normally and not-normally distributed data, respectively. After the first week, outcome measurements were analysed using independent t-tests to compare the means of continuous variables, and Chi-squared tests for categorical variables, using Fisher’s exact test when applicable. The short- and mid-term data were analysed by calculating the differences between the baseline measurement and each follow-up measurement (Δ-score). Independent t-tests were performed on the Δ-scores. All analyses were performed with IBM SPSS Statistics version 20 (IBM Corporation, Armonk, NY, USA). A p-value of p<0.05 indicated statistical significance. Calculations were done for each follow-up measurement for all patients not lost to follow-up until that point in time.

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RESULTS Study population The study took place between May 2011 and June 2017 at the orthopaedic department of a large-volume teaching hospital in the Netherlands. Out of 50 included patients, one patient in the RP group did not undergo surgery because of a significant reduction in symptoms. Not all patients completed every question in the diary during the first seven days. The entire five-year protocol was completed by 39 patients, 19 in the FP group and 20 in the RP group (Figure 1).

Figure 1. Diagram with participant flow 20/25 RP patients and 19/25 FP patients completed the total five-year follow-up measurements

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

Table 2. Patient characteristics and baseline measurements Scores Mean (SD) or N(%) Age (years) at baseline BMI (kg/m2) at baseline Duration of surgery (minutes) Blood loss (milliliters) during surgery Length of hospital stay (days) Gender Female Male Affected knee Left Right Type of anesthesia General Spinal

Baseline RP (N=24) 61 (7) 30.0 (4.1) 76.5 (15.3) 45.8 (127.6) 4.7 (1.3)

FP (N=25) 64 (9) 28.7 (3.5) 102.1 (20.4) 261.0 (200.8) 3.7 (1.8)

p-value 0.165 0.254 <.001 <.001 0.036

15 (63%) 9 (37%)

14 (56%) 11 (44%)

0.644

12 (50%) 12 (50%)

11 (44%) 14 (56%)

22 (92%) 2 (8%)

25 (100%) 0

0.674

0.235

No significant differences were found between the FP and RP groups in the preoperative measurements. Duration of surgery and blood loss were significantly higher in the FP group. LOS was shorter in the FP group. SD=standard deviation; RP=regular protocol; FP=fast-track protocol;BMI=body mass index

Patient characteristics and baseline measurements Patient groups were comparable at baseline (Table 2). Length of hospital stay (LOS) was significantly shorter for patients in the FP group (mean (SD)) 3.7 (1.8) days vs 4.7 (1.3) days, p=0.036). Duration of the surgery was significantly longer and intra-operative blood loss was higher for the FP group compared to the RP group. Four patients were discharged to a rehabilitation facility, all part of the RP group. First week measurements VAS scores for knee pain at rest were significantly lower in the FP group compared to the RP group immediately postoperative (mean (SD) RP 56 (33) vs FP 22 (31), p<0.001), at 1 hour after surgery (RP 47 (23) vs FP 25 (22), p=0.002), and at 2 hours after surgery (RP 36 (14) vs FP 23 (18), p=0.035) (Figure 2). There were no significant differences in VAS scores for knee pain at rest for the next 7 days. The VAS scores during movement were consistently lower in the FP group, with significant differences at 4 days after surgery (mean (SD) RP 25 (16) vs FP 16 (13), p=0.048) and at 6 days after surgery (RP 34 (24) vs FP 18 (14), p=0.007)

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(Figure 3). Patients in the FP group had better scores on the TUG test throughout the first week, with statistically significant differences after one day (mean (SD) RP 39 (15) vs FP 23 (10), p=0.008), four days (RP 19 (8) vs FP 14 (5), p=0.037) and six days (RP 17 (6) vs FP 13 (5), p=0.029) (Figure 4). The results of the functional questions during the first week are listed in Table 3. Significantly more patients in the FP group were able to stand on their operated leg for five seconds at day one, day two and day six. On the first day, significantly more patients in the FP group were able to do a straight leg raise. Stair climbing was not possible for any of the RP patients on the first day, compared to five patients in the FP group, which was a significant difference. No significant differences were found in the other first-week diary outcomes. Short and mid-term outcome A significant difference was found two weeks after surgery in the TUG Î&#x201D;-scores (mean (SD) RP 2.4 (3.3) seconds vs FP -0.4 (4.4), p=0.017), with the RP group showing an increase in TUG times compared to a decrease in the FP group (Table 4). There was a significant difference between the groups in the SF-12 physical score at six weeks, with the RP group showing more improvement than the FP group (mean (SD) RP 6.0 (8.1) vs FP 0.4 (7.1), p=0.021). The VAS scores for pain

100 90 80

VAS score

60 50

* *

40 30

7 Da y

6 Da y

5 Da y

4 Da y

3 Da y

2 Da y

1 Da y

Ho ur 2

Ho ur 1

ed iat ely

po s

to pe

Ba s

eli

ra tiv e

Figure 2. First week VAS scores for knee pain at rest Mean VAS scores for knee pain in rest of the RP and FP groups in the first seven days, with error bars showing standard error of the mean. Significantly lower scores in the FP group were found immediately postoperative, one hour and two hours after surgery

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

100 90 80

VAS score

60 RP

40 30 20 10 0

Baseline

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Figure 3. First week VAS scores for knee pain during movement Mean VAS scores for knee pain during movement with weight bearing of the affected knee of the FP and RP groups in the first seven days, with error bars showing standard error of the mean. Scores were lower in the FP group on all days, with significant differences on the fourth and sixth day after surgery

during knee movement at six weeks were significantly more reduced compared to baseline in the RP group than in the FP group (mean (SD) RP -51.7 (24.7) vs FP -33.8 (30.3), p=0.031). No significant differences between groups were seen after 12 weeks in both clinical and functional outcome parameters, or in any of the clinical outcome parameters at 1, 2 and 5 years after surgery (Table 5). Complications All complications are described in Table 6. The number and severity of the complications in both groups were comparable. One patient in the RP group underwent revision surgery (replacement of insert) because of persisting instability of the knee. In both groups, two patients needed manipulation of the knee because of impairment in ROM.

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50 45

TUG test scores (seconds)

40 35 30 RP

20 15 10 5 0 Baseline

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Figure 4. First week TUG test scores in seconds Mean TUG test scores in seconds of the FP and RP groups in the first seven days, with error bars showing standard error of the mean. On the fourth and sixth day postoperative the FP group was significantly faster compared to the RP group

DISCUSSION We performed a randomized controlled pilot study to evaluate functional and clinical outcome in the first seven days after surgery of patients who underwent TKA using either a regular protocol or a fast-track protocol. The study population was followed up to five years after their operation. Significant better scores on several functional outcome measures in the first week were seen in the FP group in this study compared to the RP group. This is in line with studies that showed that fast-track protocols showed improvements in reduction of LOS, complications5, and even a reduction in 30 and 90 day mortality23. These improvements have been associated with high patient satisfaction7. Comparing studies that analyze fast-track protocols is challenging, since each protocol differs to a smaller or larger extent (e.g. in approach24, use of analgesics15, or mobilization schedule6). Since fast-track protocols are aimed at starting rehabilitation sooner and mobilizing patients more quickly, this study placed more emphasis on short-term outcome, specifically the first seven days postoperatively. Our outcomes are in line with those of a few other studies that examined the effects of fast-track TKA on outcome in the first days after the procedure. Two studies, by van Egmond et al. and Winther et al.7, 14, showed reduction in pain

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

scores in the first days after fast-track TKA, but did not compare this with a regular protocol. This reduction remained visible after six weeks and one year, respectively. In the current study, the VAS scores for knee pain at rest were significantly lower in the FP group during the first two hours after surgery compared with the RP group. Also, the VAS knee pain scores for pain during knee movement were significantly lower on days four and six in the FP group. Since patients in the FP group were given fewer short-acting opiates, this reduction in pain appears to be mostly due to the combination of omitting the tourniquet, LIA and the use of ice packs. Spinal anesthesia could have influenced the pain scores in the hours after surgery, but only two patients in the RP group and no patients in the FP group had been given spinal anesthesia. It is therefore unlikely that this has influenced pain scores. A significant difference in duration of surgery was found with a longer duration in the FP group, which can largely be attributed to the use of the patellain-place balancer. When looking at functional results within the first week, the TUG test times were significantly better in the FP group on days one, four, and six. When comparing this to the literature, one study by Holm et al. also reported good results for the TUG test in 100 patients on the first days after TKA surgery with a fast-track protocol15, although this was not a controlled study. In their study, the median TUG test time at discharge (three days postoperative) was 19.2 seconds (interquartile range 25â&#x20AC;&#x201C;75% 15.3â&#x20AC;&#x201C;24.1), which is comparable to the TUG test times in the patients presented in the present study three days after surgery (Mean (SD) RP 19 (8) seconds vs FP 16 (5), p=0.109). For the other functional parameters assessed with diary questions in the first seven days, significantly more patients in the FP group were able to stand on their operated leg for five seconds on day one, two and six and were able to climb the stairs and do a straight leg raise on day one in our study. These better results in the FP group could be attributed to the subvastus approach, which, together with the patella in place balancing with no or limited soft tissue releases, could lead to the lower knee pain scores seen in the first week. When assessing these diary results, it should be noted that not all patients fully completed the questions on every day, which might have influenced these results even though patients in both groups had missing entries. However, since functional outcome has a large impact on patient satisfaction25, 26, the signs of better function found in this study in the first days after TKA when using a fast-track protocol confirm the positive effects previously observed on outcome and LOS in fast-track TKA patients. Functional and clinical short-term outcome was measured up to 12 weeks after surgery. At two weeks follow-up, patients in the FP group had improved more in

Scores Number (%) Stretched leg raise Yes No Rise from chair Yes, without help Yes, with help No Stair climbing Yes, normal Normal up, down with handrail Up and down with handrail Not possible 5 sec leg stand Yes No Scores Number (%) Stretched leg raise Yes No Rise from chair Yes, without help Yes, with help No 21 (95%) 1 (5%) 7 (33%) 13 (62%) 1 (5%) 1 (6%) 0

7 (28%) 18 (72%) 4 (17%) 18 (75%) 2 (8%) 0 0

FP 19 (95%) 1 (5%) 14 (70%) 6 (30%) 0

21 (84%) 4 (16%) 14 (58%) 10 (42%) 0

11 (58%) 8 (42%)

3 (12%) 21 (88%) Day 4 RP

0 4 (22%) 25 (100%) 13 (72%)

Day 1 RP

Table 3. First week functional test scores

0.534

p-value 0.362

0.003

0.02

0.414

p-value <.001

16 (64%) 9 (36%) 0

22 (88%) 3 (12%)

15 (60%) 10 (40%) Day 5 RP

17 (71%) 3 (12,5%)

1 (4%) 3 (12,5%)

11 (44%) 14 (56%) 0

21 (84%) 4 (16%)

Day 2 RP

16 (76%) 5 (24%) 0

19 (91%) 2 (9%)

17 (89%) 2 (11%)

16 (76%) 3 (16%)

1 (4%) 1 (4%)

9 (43%) 12 (57%) 0

20 (95%) 1 (5%)

0.522

p-value 1

0.03

0.841

p-value 0.357

17 (68%) 8 (32%)

20 (83%) 0

3 (13%) 1 (4%)

13 (52%) 12 (48%) 0

23 (92%) 2 (8%)

Day 3 RP

17 (85%) 3 (15%)

16 (76%) 2 (10%)

1 (4%) 2 (10%)

13 (62%) 8 (38%) 0

18 (86%) 3 (14%)

0.297

0.309

0.561

p-value 0.648

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1 (5%) 5 (25%) 13 (65%) 1 (5%) 18 (95%) 1 (5%) FP 20 (95%) 1 (5%) 17 (81%) 4 (19%) 0 3 (14%) 5 (24%) 12 (57%) 1 (5%) 20 (95%) 1 (5%)

3 (13%) 1 (4%) 19 (79%) 1 (4%) 17 (68%) 8 (32%) Day 6 RP 20 (80%) 5 (20%) 16 (64%) 9 (36%) 0 2 (8%) 4 (16%) 19 (76%) 0 17 (68%) 8 (32%)

0.027

0.464

0.325

p-value 0.198

0.056

0.215

18 (78%) 5 (22%)

16 (73%) 0

2 (9%) 4 (18%)

18 (78%) 5 (22%) 0

20 (87%) 3 (13%)

18 (72%) 7 (28%) Day 7 RP

17 (68%) 0

3 (12%) 5 (20%)

19 (86%) 3 (14%)

12 (55%) 1 (4%)

3 (14%) 6 (27%)

17 (77%) 5 (23%) 0

21 (95%) 1 (5%)

18 (90%) 2 (10%)

13 (65%) 1 (5%)

3 (15%) 3 (15%)

0.699

0.538

p-value 0.608

0.26

0.683

Numbers are shown of the number of patients in the RP and FP groups reporting their ability to perform a stretched leg raise, rise from a chair, climb stairs or stand on their affected leg. A significantly higher number of patients in the FP group was able to stand on their operated leg for five seconds on day one, two and six and were able to climb the stairs and do a straight leg raise on day one. RP=regular protocol; FP=fast-track protocol

Stair climbing Yes, normal Normal up, down with handrail Up and down with handrail Not possible 5 sec leg stand Yes No Scores Number (%) Stretched leg raise Yes No Rise from chair Yes, without help Yes, with help No Stair climbing Yes, normal Normal up, down with handrail Up and down with handrail Not possible 5 sec leg stand Yes No

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

40 0.527

0.58 0.189

0.954 0.234 -9 (13) -1 (6)

-13 (18) -1 (5)

-10 (18) -1 (4)

0.376 0.917

0.495 0.357

-22 (16) -5 (6)

20.8 (25.2)

0.457 0.151 0.073 0.976

-20 (14) -3 (7)

24.9 (19.3)

2.1 (22.5) 12.7 (21.5) 15.0 (27.0) 6.9 (23.4)

0.021 0.139

-7 (14) 0 (6)

0.549

7.0 (23.2) 21.3 (19.5) 28.7 (24.7) 6.7 (25.1)

0.4 (7.1) 1.0 (8.1)

p-value

-19 (15) -4 (7)

19.5 (26.3)

15.4 (20.3)

0.848 0.532 0.49 0.86

6.0 (8.1) -2.4 (6.1)

FP Mean (SD)

-19 (14) -2 (6)

4.2 (24.5) 15.2 (19.1) 13.7 (22.3) -1.0 (21.4)

5.3 (17.4) 18.7 (19.4) 18.1 (21.9) 0.0 (17.8)

0.973 0.784

6 weeks RP Mean (SD)

-51.7 (24.7) -33.8 (30.3) 0.031 -23.3 (27.7) -14.0 (26.7) 0.250 -0.2 (3.0) -1.7 (3.3) 0.116

-0.2 (4.5) 0.6 (8.0)

-0.2 (4.6) 0.0 (4.6)

p-value

-46.1 (24.4) -38.6 (30.8) 0.358 -18.5 (35.3) -15.0 (27.7) 0.705 2.4 (3.3) -0.4 (4.4) 0.017

FP Mean (SD)

2 weeks RP Mean (SD)

34.3 (29.0)

10.9 (26.1) 26.2 (24.8) 22.4 (26.1) 14.8 (24.2)

5.3 (7.5) -0.6 (5.8)

FP Mean (SD)

0.395

0.362 0.693 0.324 0.438

0.397 0.965

p-value

0 (16) 1 (6)

1 (16) 1 (6)

-3 (15) 1 (6)

0.428 0.981

0.45 0.868

-48.4 (26.5) -37.3 (29.7) 0.184 -20.5 (27.8) -21.1 (23.7) 0.943

27.8 (23.0)

16.9 (18.0) 29.0 (23.3) 29.5 (23.0) 21.0 (30.2)

7.4 (8.5) -0.7 (5.6)

12 weeks RP Mean (SD)

Mean change (Δ-scores) for the SF-12, KOOS, VAS for knee pain, TUG and knee ROM are shown at two, six and twelve weeks postoperatively. TUG test times were faster in the FP group after two weeks. SF-12 and VAS for knee pain during movement scores had improved more in the RP group after six weeks. Data in Mean (standard deviation); Δ-scores = score at follow-up moment minus baseline score; KOOS = Knee Injury and Osteoarthritis Outcome Score; RP = regular protocol; FP = fast-track protocol; ADL = Activities of Daily Living

Δ-scores SF-12 Physical Score Mental Score KOOS Symptoms score Pain score ADL score Sport & Recreation score QoL score VAS Movement Rest TUG (seconds) ROM (degrees) Passive Flexion Extension Active Flexion Extension

Table 4. Short-term outcome parameters

PART 1 | C H APTE R 2

FP Mean (Sd) 4.9 (9.3) 6.2 (9.0) 22.9 (31.4) 34.3 (29.3) 28.5 (27.6) 31.0 (32.3) 39.7 (30.3)

1 year RP Mean (Sd)

9.4 (12.8) 7.1 (7.1)

33.7 (19.1) 45.0 (19.8) 41.6 (18.8) 42.9 (28.8)

40.7 (19.6)

0.896

0.183 0.177 0.091 0.215

0.243 0.751

p-value

40.1 (24.4)

30.1 (18.3) 41.3 (21.9) 37.9 (25.3) 36.5 (35.6)

6.2 (16.3) 7.0 (8.1)

2 years RP Mean (Sd)

45.1 (26.7)

35.7 (23.4) 40.8 (25.9) 35.1 (21.3) 36.9 (32.0)

6.0 (10.5) 8.8 (6.2)

FP Mean (Sd)

0.567

0.429 0.95 0.739 0.973

0.969 0.546

p-value

46.0 (28.4) -43.5 (33.5) -20.9 (23.8)

-54.3 (26.0) -21.0 (18.1)

37.0 (23.9) 27.0 (30.6) 28.1 (24.5) 38.1 (27.0)

7.4 (9.6) 6.1 (8.6)

FP Mean (Sd)

44.2 (22.4)

41.1 (16.9) 34.3 (22.4) 33.6 (21.2) 47.0 (27.0)

9.4 (13.7) 7.6 (9.2)

5 years RP Mean (Sd)

0.315 0.986

0.830

0.566 0.409 0.463 0.334

0.689 0.645

p-value

This table shows mean change (Δ-scores) for the SF-12, KOOS and VAS for knee pain for the one, two and five year follow-up measurements. No significant differences between the RP and FP groups were found. Data in Mean (standard deviation); Δ-scores = score at follow-up moment minus baseline score; KOOS = Knee Injury and Osteoarthritis Outcome Score; RP = regular protocol; FP = fast-track protocol; ADL = Activities of Daily Living

Δ-scores SF-12 Physical Score Mental Score KOOS Symptoms score Pain score ADL score Sport & Recreation score QoL score VAS knee pain Movement Rest

Table 5. Mid-term outcome parameters

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

PART 1 | C H APTE R 2

Table 6. Complications Regular protocol Complication Manipulation (2x) Revision surgery (new insert because of instability) Limited knee extension, treated with cast Swelling, treated with intra-articular injection Urinary tract infection Meralgia paraesthetica

Time after surgery 3 & 4 months 1 year 10 weeks 1,5 years

Fast-track protocol Complication Manipulation (2x) Pain on lateral side of knee, treated with injection (2x) Fractured patella after fall Patellar instability, treated with brace

Time after surgery 3 & 4 months 10 months 1,5 years 1 year

Directly postoperative Directly postoperative

The number and severity of the complications observed were comparable for the RP and FP groups.

the TUG test, but this effect disappeared after 6 weeks. This could indicate that the FP group functioned better after 2 weeks, but the other functional outcome parameters did not show similar effects. Change in ROM of the knee did not differ between the RP and FP groups. It is known that pre-operative ROM influences both LOS27 and post-operative ROM28. However, since pre-operative ROM did not differ between groups, this cannot have biased the postoperative results. TKA has been known to positively affect QoL of patients with osteoarthritis of the knee29, although this has not been extensively described for short-term follow-up. The SF-12 physical score after 6 weeks showed a significantly stronger improvement in the RP group than in the FP group. This could have been due to more post-operative pain, since the FP group received less pain medication as part of their protocol. However, this difference was not found after two weeks, and the VAS scores for knee pain in rest and during knee movement also did not differ significantly between the two groups after six weeks. In both groups, patients scored at a level deemed satisfactory after 12 weeks30 for the KOOS, SF-12 and VAS knee pain scores. This is contrary to other studies, which found a positive effect on clinical outcome when using a fast track protocol6, 7 compared to a regular protocol. However, these studies used a different outcome score (Knee Society Score), which might partly explain why different results were reported. At mid-term follow-up after one and two years, no significant differences were found in function, pain and QoL, which confirms the results reported by

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

earlier studies7. This same pattern was found five years after surgery in the KOOS, SF-12 and VAS knee pain scores. To our knowledge, at the time of writing there were no comparable studies that presented five-year follow-up data of fast-track compared to regular TKA, hence no comparison to literature could be made. A fast-track protocol usually contains several parts that are aimed at improving outcome. For studies evaluating fast-track protocols in general, but especially for a smaller study population as in the current study, it is difficult to determine which parts of the fast-track protocol do or do not contribute to the observed effect on outcome. To determine for each individual element of the fast-track protocol whether it contributes to the outcome, a large number of studies is required. Since a possible contribution would probably have a small effect, large numbers of included patients will be needed. It is therefore also possible that several modifications from the fast-track protocol did not contribute to the positive results found in this study. Furthermore, several hospitals are already experimenting with a next step in fast-track protocol: outpatient TKA surgery. Even though this is relatively new, there have been some signs showing that the experiences gained in fast-track TKA surgery are being used to help patients return home even earlier31. One outcome measurement that was not studied but could be of interest is costeffectiveness. There are studies showing that fast-track protocols are cost-effective in TKA and total hip arthroplasty32. This could be due to several factors. First, fast-track protocols could reduce costs because of a reduction in LOS. If all patients left the hospital 1-2 days earlier than usual, regular costs of hospital admittance would decrease. Also, a longer LOS is associated with an increased use of hospital resources33. Secondly, fast-track protocols could result in better cost-effectiveness because patients that have better function when discharged from hospital would require less pain medication, a lower number of physiotherapy treatments and a lower number of days spent in rehabilitation centers, and they would be able to return to work sooner34, 35. Limitations There are several limitations to this study. Comorbidities have not been accounted for, even though patientsâ&#x20AC;&#x2122; comorbidities can influence outcome after TKA36, 37. This issue has partly been addressed by only including ASA I and II patients. Similarly, a patientâ&#x20AC;&#x2122;s perception of his/her hospital stay has not been taken into account, even though this has been shown to influence patient functional outcome and satisfaction38. We aimed to tackle both these issues by using a randomized

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allocation of subjects to the study groups. As described, patients were told before surgery that the aim of the FP was to discharge patients after two days, which means that it is possible that the LOS outcome was influenced by motivational bias, since patients were focused from the beginning on an early discharge.

CONCLUSIONS This randomized controlled pilot study comparing the early results of primary TKA patients in a fast-track TKA protocol and a regular protocol showed indications that even with the significantly quicker discharge from hospital associated with fast-track TKA, patients in the fast-track group had lower knee pain scores and better functional outcome in the first seven days after surgery. Since this only a pilot study, no firm conclusions can be drawn. However, since fast-track protocols for TKA are being implemented in most orthopaedic practices, more emphasis of research on the first days after TKA may provide more opportunities for further improving outcome in fast-track TKA patients. Conflict of interest statement This study was partly funded by Stryker, Mahwah, USA. They did not play a role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and/or in the decision to submit the article for publication.

FA ST-TRACK TKA IMPROVES OUTCOME IN THE FIRST 7 DAYS

REFERENCES 1. Liddle AD, Pandit H, Judge A, Murray DW (2015) Patient-reported outcomes after total and unicompartmental knee arthroplasty: a study of 14,076 matched patients from the National Joint Registry for England and Wales. Bone Joint J 97–B:793–801 2. Shan L, Shan B, Suzuki A, et al (2015) Intermediate and long-term quality of life after total knee replacement: a systematic review and meta-analysis. J Bone Joint Surg Am 97:156–68 3. Kievit AJ, van Geenen RCI, Kuijer PPFM, et al (2014) Total knee arthroplasty and the unforeseen impact on return to work: a cross-sectional multicenter survey. J Arthroplasty 29:1163–8 4. Maradit Kremers H, Larson DR, Crowson CS, et al (2015) Prevalence of Total Hip and Knee Replacement in the United States. J Bone Jt Surg 97:1386–1397 5. Kehlet H (2013) Fast-track hip and knee arthroplasty. Lancet (London, England) 381:1600–2 6. den Hertog A, Gliesche K, Timm J, et al (2012) Pathway-controlled fast-track rehabilitation after total knee arthroplasty: a randomized prospective clinical study evaluating the recovery pattern, drug consumption, and length of stay. Arch Orthop Trauma Surg 132:1153–63 7. Winther SB, Foss OA, Wik TS, et al (2015) 1-year follow-up of 920 hip and knee arthroplasty patients after implementing fast-track. Acta Orthop 86:78–85 8. Sutton JC, Antoniou J, Epure LM, et al (2016) Hospital Discharge within 2 Days Following Total Hip or Knee Arthroplasty Does Not Increase Major-Complication and Readmission Rates. J Bone Joint Surg Am 98:1419–28 9. Pamilo KJ, Torkki P, Peltola M, et al (2017) Fast-tracking for total knee replacement reduces use of institutional care without compromising quality. Acta Orthop 1–6 10. Husted H, Otte KS, Kristensen BB, et al (2010) Readmissions after fast-track hip and knee arthroplasty. Arch Orthop Trauma Surg 130:1185–1191 11. El Bitar YF, Illingworth KD, Scaife SL, et al (2015) Hospital Length of Stay following Primary Total Knee Arthroplasty: Data from the Nationwide Inpatient Sample Database. J Arthroplasty 12. Pitter FT, Jørgensen CC, Lindberg-Larsen M, et al (2016) Postoperative Morbidity and Discharge Destinations After Fast-Track Hip and Knee Arthroplasty in Patients Older Than 85 Years. Anesth Analg 122:1807–1815 13. Jørgensen CC, Kehlet H (2013) Role of patient characteristics for fast-track hip and knee arthroplasty. Br J Anaesth 110:972–980 14. Van Egmond JC, Verburg H, Mathijssen NMC (2015) The first 6 weeks of recovery after total knee arthroplasty with fast track. Acta Orthop 86:708–713 15. Holm B, Kristensen MT, Myhrmann L, et al (2010) The role of pain for early rehabilitation in fast track total knee arthroplasty. Disabil Rehabil 32:300–6 16. (2013) World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA 310:2191–4 17. Schulz KF, Altman DG, Moher D (2010) CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials. PLoS Med 7:e1000251 18. Dixon JR The International Conference on Harmonization Good Clinical Practice guideline. Qual Assur 6:65–74 19. Keijsers R, van Delft R, van den Bekerom MPJ, et al (2015) Local infiltration analgesia following total knee arthroplasty: effect on post-operative pain and opioid consumption—a meta-analysis. Knee Surgery, Sport Traumatol Arthrosc 23:1956–1963 20. Podsiadlo D, Richardson S (1991) The timed Up & Go: a test of basic functional mobility for frail elderly persons. J Am Geriatr Soc 39:142–8 21. de Groot IB, Favejee MM, Reijman M, et al (2008) The Dutch version of the Knee Injury and Osteoarthritis Outcome Score: a validation study. Health Qual Life Outcomes 6:16 22. Gandek B, Ware JE, Aaronson NK, et al (1998) Cross-validation of item selection and scoring for the SF-12 Health Survey in nine countries: results from the IQOLA Project. International Quality of Life Assessment. J Clin Epidemiol 51:1171–8 23. Malviya A, Martin K, Harper I, et al (2011) Enhanced recovery program for hip and knee replacement reduces death rate. Acta Orthop 82:577–81

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24. Verburg H, Mathijssen NMC, Niesten D-D, et al (2016) Comparison of Mini-Midvastus and Conventional Total Knee Arthroplasty with Clinical and Radiographic Evaluation: A Prospective Randomized Clinical Trial with 5-Year Follow-up. J Bone Joint Surg Am 98:1014–22 25. Matsuda S, Kawahara S, Okazaki K, et al (2013) Postoperative alignment and ROM affect patient satisfaction after TKA. Clin Orthop Relat Res 471:127–33 26. Williams DP, O’Brien S, Doran E, et al (2013) Early postoperative predictors of satisfaction following total knee arthroplasty. Knee 20:442–6 27. van den Belt L, van Essen P, Heesterbeek PJC, Defoort KC (2015) Predictive factors of length of hospital stay after primary total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 23:1856– 62 28. Gatha NM, Clarke HD, Fuchs R, et al (2004) Factors affecting postoperative range of motion after total knee arthroplasty. J Knee Surg 17:196–202 29. Ethgen O, Bruyère O, Richy F, et al (2004) Health-related quality of life in total hip and total knee arthroplasty. A qualitative and systematic review of the literature. J Bone Joint Surg Am 86– A:963–74 30. Giesinger JM, Hamilton DF, Jost B, et al (2015) WOMAC, EQ-5D and Knee Society Score Thresholds for Treatment Success After Total Knee Arthroplasty. J Arthroplasty 30(12):2154-8. 31. Vehmeijer SBW, Husted H, Kehlet H (2017) Outpatient total hip and knee arthroplasty. Acta Orthop 89(2):141-144 32. Larsen K, Hansen TB, Thomsen PB, et al (2009) Cost-Effectiveness of Accelerated Perioperative Care and Rehabilitation After Total Hip and Knee Arthroplasty. J Bone Jt Surgery-American Vol 91:761–772 33. Stowers MDJ, Manuopangai L, Hill AG, et al (2016) Enhanced Recovery After Surgery in elective hip and knee arthroplasty reduces length of hospital stay. ANZ J Surg 86(6):475-9. 34. Klit J (2014) Results of total joint arthroplasty and joint preserving surgery in younger patients evaluated by alternative outcome measures. Dan Med J 61:B4836. 35. Tilbury C, Schaasberg W, Plevier JWM, et al (2014) Return to work after total hip and knee arthroplasty: a systematic review. Rheumatology (Oxford) 53:512–25 36. Stone OD, Duckworth AD, Curran DP, et al (2015) Severe arthritis predicts greater improvements in function following total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 25(8):25732579 37. Elmallah RDK, Cherian JJ, Robinson K, et al (2015) The Effect of Comorbidities on Outcomes following Total Knee Arthroplasty. J Knee Surg 28:411–6 38. Clement ND, Macdonald D, Burnett R, et al (2017) A patient’s perception of their hospital stay influences the functional outcome and satisfaction of total knee arthroplasty. Arch Orthop Trauma Surg 137:693–700

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CHAPTER 3 No differences between fixed- and mobile-bearing total knee

Knee Surgery, Sports Traumatology, Arthroscopy. 2017 Jun;25(6):1757-1777. BL Fransen, DC van Duijvenbode, MJM Hoozemans, BJ Burger

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ABSTRACT Purpose For years, numerous studies have been performed to determine whether mobile bearing total knee arthroplasty (MB-TKA) or fixed bearing total knee arthroplasty (FB-TKA) is the preferential design in total knee arthroplasty. Reviews and metaanalyses on this subject have focused on a relatively small number of randomized controlled trials, possibly missing important results of smaller studies. The goal of this review was to provide a comprehensive overview of all literature comparing MB-TKA and FB-TKA in the treatment of osteoarthritis of the knee. Methods An extensive literature search was performed in the PUBMED database. All studies that compared MB-TKA with FB-TKA and looked at one of four theorized advantages (insert wear, signs of loosening, survival rate of the prosthesis and clinical outcome) were included. Results The initial search yielded 258 articles, of which 127 were included after the first screening. The included studies consisted of 9 meta-analyses, 3 systematic reviews, 48 RCTâ&#x20AC;&#x2122;s, 44 comparative studies, 10 reviews and 13 studies that examined patients who received bilateral TKA (one MB-TKA and one FB-TKA). Combining the results of all studies showed that almost all studies found no difference between MB-TKA and FB-TKA. Conclusions Even when examining all different types of studies on MB-TKA and FB-TKA, the results of this review showed no difference in insert wear, risk of loosening, survivorship, or clinical outcome. In daily practice, the choice between MB-TKA and FB-TKA should be based on the experience and judgment of the surgeon, since no clear differences are observed in the scientific literature.

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

INTRODUCTION Since the first mobile bearing total knee arthroplasty (MB-TKA) procedures have been performed in the 1980’s21, numerous scientific studies have compared MBTKA with fixed bearing total knee arthroplasty (FB-TKA)3, 21, 55, 95, 100, 130, 133. The mobile bearing design was developed to allow rotation of the insert around the longitudinal axis (“rotating platform”) or to allow anterior-posterior translation between the insert and the tibial tray of the prosthesis (“meniscal bearing”). Due to the rotational and the translational properties between the insert and the tibial tray, the mobile bearing insert can be modelled such that they have a better fit with the femoral component without compromising the natural rotation and translation between femur and tibia. This is contrary to the fixed inserts in FB-TKA, which are relatively flat and, therefore, allow some small rotations and translations, but much smaller compared to the MB-TKA105. MB-TKA has been theorised in the literature to result in four advantages over FB-TKA: reduced insert wear, less risk of loosening, fewer revisions and better clinical outcome. Firstly, MB-TKA is expected to result in less polyethylene wear because of a larger contact surface between the femoral component and the insert, induced by a more optimal fit of the femoral component and the insert30. In addition, the insert can rotate and translate relative to the tibial component, which means that the femoral component slides less on the surface of the insert, which also potentially results in less wear. Secondly, MB-TKA is hypothesized to reduce the chance of loosening of the prosthesis because of less osteolysis30. This is thought to be due to the movement of the insert on the tibial tray, resulting in less stress on the bone-cement interface of the tibial component, and less wearinduced osteolysis. The third advantage described in literature is that less wear and loosening results in a lower number of revisions and, therefore, a better survivorship of the prosthesis20. The final theorised advantage of MB-TKA is better clinical outcome. The mobility and design of the insert is hypothesized to result in a more natural movement of the prosthetic knee in daily life. Several disadvantages of MB-TKA have also been described. A known complication of MB-TKA is dislocation of the insert51, 130. During surgery, a high level of precision in balancing of the flexion and extension gap is necessary to prevent dislocation or spin-off of the insert. Therefore, MB-TKA is acknowledged to be associated with a prolonged learning curve and an increased risk of soft tissue impingement30. Additionally, the fact that in MB-TKA there is a second articulating surface could be a risk for increasing wear as a larger surface of the insert is exposed to friction30, 130.

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In particular in the last ten years, an increased number of high quality articles have been published that have studied one or more of the four theorised advantages of MB-TKA. Reviews and meta-analyses have been performed to provide an overview of all the literature available, none finding any significant differences. However, these often include the same studies with a high level of evidence. Several studies have been performed that provide valuable information on MBTKA and FB-TKA, but are omitted from these overviews because of their methodology. The goal of the present paper is to present an up-to-date overview of the scientific literature that includes studies of different levels of evidence that compare cemented MB-TKA with cemented FB-TKA with respect to insert wear, signs of loosening of the prosthesis, survivorship of the prosthesis and clinical outcome, and to arrive at an evidence based advise with regard to the preferable type of insert.

MATERIALS AND METHODS Search strategy The PubMed Medline database was searched for English language meta-analyses, (systematic) reviews, randomised controlled trials and comparative studies. The search terms used were: mobile bearing, rotating platform, meniscal bearing and anterior-posterior glide-rotation. Fixed and total or TKA needed to be present as keywords. Unicompartmental and hemi were excluded in the search. The last search was performed on 17 February 2015. The complete search string can be found in the Appendix, Table 1. Eligibility criteria Two independent reviewers (BF and DD) screened the results of the search, first using the title and abstract of the articles and second using the full text of the remaining articles to identify those eligible for inclusion. Studies comparing clinical, radiological and/or functional results of MB-TKA and FB-TKA were eligible for inclusion. The primary indication for TKA had to be osteoarthritis. In vitro studies, studies with kinematic results or studies that used biomechanical models were excluded, as well as studies that focused on complete polyethylene tibial components or uncemented prostheses. In the current study, no differentiation was made between meniscal bearing and rotating platform subtypes of MB-TKA or between cruciate retaining and posterior stabilized prostheses. Eligible articles of which the full text could be retrieved and which reported results

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

on one or more of the four theorised advantages of MB-TKA were included. Wear of the insert had to be assessed by measuring the thickness of retrieved inserts, or using the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System35, or similar radiological measurement methods. The risk of loosening of the prosthesis had to be reported in the form of radiolucencies or osteolysis around the bone-cement interface. With respect to survivorship and the number of revisions only those studies were included that reported survival as a result of aseptic loosening. Clinical outcome had to be compared by patientreported outcome questionnaires looking at pain and functional impairment, or by measuring the range of motion by looking at flexion and extension of the knee. In the case of disagreement about an article this was resolved through a discussion between the reviewers. Data collection The following information was extracted from the included studies: author, year of publication, study design (meta-analysis, (systematic) review, randomised controlled trial, comparative study), level of evidence, type of prosthesis, number of prostheses, age of the MB group, age of the FB group and duration of followup. In addition, the main results of the articles were studied to see what results they reported for each of the four main outcome categories. For each outcome category that was reported in the article the result was summarised as either MB=FB (no difference between MB-TKA and FB-TKA), MB (outcome favours MBTKA) or FB (outcome favours FB-TKA). When several follow-up measurements were reported within a study, the final measurements were used for summarizing the results. If a study did not perform a statistical analysis on an outcome category, no result was formulated for that specific category. If a study did not report consistent results within one of the four main outcome categories, there was no final conclusion made for that particular category. If a preference for a type of bearing was reported by patients who participated in bilateral comparative studies, this was also registered. Data analysis Final conclusions were based on the studies with the highest level of evidence (LoE), as determined by the reviewers using the criteria reported by several orthopaedic journals108, 117, 140. Bilateral comparative studies (where patients received a MB-TKA in one knee and a FB-TKA in the other knee) were considered as level 1 and non-systematic reviews as level 3. If information needed for determining the level of evidence was missing, the level of evidence was reported as one level lower.

PART 1 | C H APTE R 3

Because of the large amount of studies included in the current overview, conclusions on the four main categories were primarily drawn by analyzing the studies with LoE 1, since these studies are considered to have the highest methodological quality. Afterwards, the results from studies with LoE 2 and 3 were analyzed to see whether the results from those studies provided a different view.

RESULTS Search, selection and study characteristics The PubMed search resulted in 258 articles, 121 of which were excluded based on abstract or title (Figure 1). A full text version was retrieved of the remaining 137 studies. After reading the full text another 10 articles were excluded. Six of them did not report on the predetermined outcome variables, two articles had included uncemented prostheses in their analyses, and two articles were excluded because of comparing their own MB-TKA data with literature instead of their own FB-TKA data. All 127 studies are described in table 1. The included studies consisted of 44 comparative studies (CS), 48 randomized controlled trials (RCT), 13 bilateral studies that compared MB-TKA in one knee and FB-TKA in the other (BiL), 10 reviews (R), three systematic reviews (SR) and nine meta-analyses (MA). No articles from before 2001 were found. Figure 2 shows the number of included papers that was published each year. Insert wear Results of the LoE 1 studies that reported on insert wear are detailed in table 2. All five studies, two of which were bilateral studies, did not find a difference between MB-TKA and FB-TKA when looking at the radiological signs of insert wear. When looking at the LoE 2 and 3 studies, all LoE 2 studies and four out of seven LoE 3 studies did not find a difference between MB-TKA and FB-TKA (Appendix Table 2). Three LoE 3 studies reported a significant difference in wear in favour of MB-TKA. Signs of loosening of the prosthesis Twenty-eight LoE 1 studies reported radiolucencies or osteolysis (Table 3). All studies except for 1 reported no difference for any of these variables. The exception was an RCT by Bailey et al.5, who reported a significantly higher percentage of radiolucencies around the tibial component in MB-TKA. The LoE 2 and 3 studies did not find a difference between MB-TKA and FB-TKA (Appendix Table 3).

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

Figure 1. Study flow diagram conform PRIMA statement86

Survivorship Table 4 shows all results on survival rate and number of revisions. Twenty-five LoE 1 studies were included, and none of these found a significant difference in either survival or revision rate between MB-TKA and FB-TKA. One LoE 2 study and three LoE 3 studies reported a significant difference in favour of FB-TKA for this parameter (Appendix Table 4).

Year

2013 2005 2011 2013 2015 2011 2003 2004 2004 2007 2012 2005 2006 2014 2014 2013 2008 2014 2003 2013

2013 2001 2006

Author

Aggarwal [1] Aglietti [2] Apostolopoulos [3] Argenson [4] Bailey [5] Ball [6] Banks [7] Banks [8] Banks [9] Beard [10] Berry [11] Bhan [12] Biau [14] Bistolfi [15] Bo [16] Breeman [17] Breugem [18] Breugem [19] Catani [22] Chen [23]

Cheng [24] Chiu [25] Delport [27]

MA BiL CS

RCT RCT R CS RCT RCT CS CS CS BiL CS BiL CS CS MA RCT RCT RCT CS CS 1 1 3

1 2 3 3 1 1 3 3 3 1 3 1 3 2 2 2 1 2 3 3

Scorpio MB Stryker; Duracon FB Stryker MBK MB Zimmer; LPS FB Zimmer Multiple PFC Sigma CR MB/FB DePuy Scorpio MB/FB Stryker Multiple Multiple Multiple TMK MB Biomet; AGC FB Biomet PFC-Sigma MB/FB DePuy LCS MB DePuy; Burstein II FB Zimmer Hopital Lyon Sud MB/FB Tornier NexGen LPS MB/FB Zimmer Multiple Multiple (not specified which) NexGen Legacy MB/FB Zimmer NexGen LPS PS MB/FB Zimmer Insall Burstein II FB Zimmer; MBK MB Zimmer PFC Sigma De Puy FB/MB; Genesis II FB Smith & Nephew Multiple AMK FB DePuy; LCS MB DePuy Performance MB/FB Biomet

Study LoE Type of prothesis type

Table 1. Characteristics of included studies

1821 16/16 14/21

516/330 161/170 51/42 29/92 12/47 44/169 33/33 94/218 16/16 42/47 100/100 1614 276/263 47/53 29/40 10/10 106/97

Number of protheses (MB/FB) 29/27 65/65

63 (40-71) 71 70 (43-87) 69 (±9) 71 (53-87) 80 (56-88) 68 (59-76) 64.4 (±16)

63 (40-71) 71 70 (57-83) 69 (±8) 68 (29-86) 78 (62-95) 62 (59-80) 67.6 (±7)

68 (51-79)

63 (47-67)

68 (51-79)

71 70 (±8) 64 70 (±8)

55 (41-65) 70

2 (1.3-2.2) 13 (12-24)

3.7 (3-4.7) 3-6 6.0 (4.5-7.5) 5 2.3 2 - 16.8 5 1 7.9 (6-10) 0.7-2.2 2.7 (0.7 - 4.3)

min. 10yr 2 >2 26 (±13)

4 - 6.5 3 (2.5-4.0)

Age FB (yrs) Follow-up (yrs)

71 69 (±9) 65 70 (±8)

60 (48-76) 71

Age MB (yrs)

PART 1 | C H APTE R 3

Year

2013 2003 2004 2005 2006 2013 2006 2014 2008 2013 2014 2005

2010 2009 2009 2006 2009 2007 2015 2002

2002

2007

Author

Delport [26] Dennis [31] Dennis [32] Dennis [29] Dennis [30] Engh [33] Evans [34] Ferguson [36] Geiger [37] Gothesen [38] Gupta [40] Hansson [42]

Hanusch [43] Harrington [44] Hasegawa [45] Henricson [46] Higuchi [47] Ho [48] Hofstede [49] Huang [52]

Huang [53]

Huang [50]

RCT RCT BiL RCT RCT CS SR CS

CS CS CS R R CS CS RCT CS CS CS RCT

1 2 1 1 2 3 2 3

2 3 3 3 3 3 3 1 3 3 3 1

Performance MB/FB Biomet Multiple Multiple Multiple LCS MB DePuy; Sigma MB/FB DePuy PFC Sigma MB/FB DePuy PFC Sigma MB/FB DePuy E.motion MB Aesculap; PFC FB Depuy Multiple Multiple Rotaglide total knee System MB Corin Medical; Nuffield total knee System FB Corin Medical PFC Sigma MB/FB DePuy PFC Sigma MB/FB DePuy PFC Sigma MB/FB DePuy NexGen CR FB Zimmer; MBK MB Zimmer PFC Sigma MB/FB DePuy LCS MB DePuy; MG 1 FB Zimmer Multiple LCS MB DePuy; PCA FB Howmedica; AMK FB DePuy; MG 1 FB Zimmer; Richards Tricon FB S&N; LCS MB Depuy; LCS PS MB DePuy; AMK FB DePuy; PCA FB Howmedica; MG 1 FB Zimmer; Richards Tricon FB S&N; Multiple

Study LoE Type of prothesis type

34/46

67 (±7)

65 (±9)

34/37

67 (±7)

69 (±7)

70 63 (43-82) 74 (55-81) 72 (62-83) 68 (56-81) 59 (40-74)

66 (±11) 75 (64-86)

65 (±13) 74 (60-85) 69 64 (38-85) 73 (55-81) 72 (62-84) 68 (56-81) 59 (48-73)

61 (40-79) 68 (±9) 70 (±8) 70

1.1 (0.8-2.4) 2 3.3 (1.5-5.3) 2 4 9.6 (4.0-13.5)

>2 2 2 1.8-6.9

5 (0.25-17)

Age FB (yrs) Follow-up (yrs)

59 (39-76) 63 (±8) 70 (±8) 69

50/55 86/72 25/25 23/26 31/45 15/36

12/12 113/100 163/176 30/30 6320/11452 114/397 25/27

Number of Age MB protheses (yrs) (MB/FB) 267/885 97/127 80/187

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

Year

2009 2011 2004 2011 2012 2012 2012 2001 2007 2007

2009 2009 2010 2010

2012 2012 2012 2005 2008 2011 2014 2009 2012

Author

Huang [51] Huang [54] Jacobs [55] Jacobs [56] Jawed [57] Jolles [58] Kalisvaart [59] Kim [67] Kim [64] Kim [68]

Kim [65] Kim [69] Kim [63] Kim [61]

Kim [62] Kim [60] Kim [66] Kotani [70] Lädermann [71] Lampe [72] Li [73] Liu [74] Lizaur [75]

CS RCT BiL CS RCT RCT MA CS RCT

BiL RCT CS RCT

R R SR RCT BiL RCT RCT BiL BiL BiL

3 1 1 2 1 1 2 3 1

1 1 3 1

3 3 2 2 1 1 1 1 1 1 LCS MB DePuy; AMK FB DePuy Medial Pivot FB Wright; PFC Sigma MB DePuy Multiple E.motion-FP MB B.Braun; Genesis II FB Smith & Nephew LPS Flex MB/FB Zimmer Sigma RP MB DePuy; NexGen LPS Flex FB Zimmer LCS MB DePuy; AMK FB DePuy Genesis II MB/FF Smith&Nephew PFC Sigma MB/FB Depuy Columbus MB/FB B.Braun Aesculap Multiple LPS Flex MB/FB Zimmer Trekking MB Samo; Multigen Plus FB Lima

Multiple BalanSys MB/FB Mathys Medical PFC Sigma MB/FB DePuy NexGen LPS MB/FB Zimmer PFC Sigma MB/FB DePuy LCS MB DePuy; AMK FB DePuy PFC Sigma MB/FB DePuy LCS MB DePuy; AMK FB DePuy

Study LoE Type of prothesis type

32/34 37/36 108/108 24/195 44/48 48/52 1659/1638 41950 61/58

61/61 92/92 816/894 66/66

46/46 50/50 26/29 76/76 116/116 174/174 146/146

66 (±6) 45 (29-50) 70 69 (53-84) 72 74 (70-82)

72 70 (52-84) 72 75 (70-83)

48 (34-55) 70 (55-81) 59 (33-65) 70 (55-79)

70 (42-80)

67 3.3 (3.0-3.9) 70 (±7) 67 (±8) 66 (33-70)

1 2.5-2.6 16.8 (15-18) >2 7.1 (5.8-7.8) 1 >1

13.2 (11.0-14.5) 10.8 (10-12) 2.6 (2-3) 12.8 (10-17) 2

5 5 7.4 (6-8)

Age FB (yrs) Follow-up (yrs)

68 (±6) 45 (29-50)

48 (34-55) 70 (55-81) 56 (33-65) 70 (55-79)

68 3.3 (3.0-3.9) 67 (±8) 67 (±8) 65 (33-70) 5.6 (5.2-6.1) 70 (42-80)

Number of Age MB protheses (yrs) (MB/FB)

PART 1 | C H APTE R 3

Year

2010

2006 2012 2014

2010 2014 2010 2015 2014 2010 2011 2012 2013

2012 2009 2014 2004 2012 2010 2003 2013

2010

Author

Lu [76]

Luring [77] Mahoney [79] Marques [80]

Matsuda [81] McGonagle [83] Minoda [84] Minoda [85] Moskal [87] Munro [89] Namba [91] Namba [90] Nieuwenhuijse [92]

Nutton [93] Oh [95] Okamoto [96] Pagnano [97] Pijls [98] Post [100] Price [101] Radetzki [102]

Rahman [103]

RCT

RCT MA RCT RCT RCT R BiL RCT

RCT CS CS RCT MA RCT R CS RCT

CS RCT RCT

1 1 1 2 2 3 1 2

1 2 3 1 1 1 3 2 1

3 2 1

LCS MB Depuy; PCA FB Howmedica; MG FB Zimmer VectorVision MB Brainlab; PCF Sigma FB Depuy Scorpio PS MB/FB Stryker Columbus RP MB B.Braun; Columbus CR FB B. Braun NexGen LPS Flex MB/FB Zimmer Rotaglide + MB/FB Corin Medical NexGen LPS Flex FB; PFC Sigma MB Vanguard PS MB/FB Biomet Multiple PFC Sigma MB/FB DePuy Multiple NexGen LPS MB/FB Zimmer; NexGen LPS Flex MB/ FB Zimmer PFC Sigma MB/FB DePuy Multiple NexGen LPS Flex MB/FB Zimmer PFC Sigma MB/FB DePuy Interax MB/FB Stryker-Howmedica TMK MB Biomet; ACG FB Biomet NexGen LPS FB Zimmer; Nexgen LPS Flex MB Zimmer PFC Sigma MB/FB DePuy

Study LoE Type of prothesis type

68 (50-79)

67 (47-83)

10-12 1 10.8 (±0.8) 3.3/3.6

75 (±8) 62 (44-78)

73 (±11)

39/39 17/22

63 (52-72)

78 (70-84) 67 (41-80) 66 (±14)

76 (65-88) 67 (41-80) 64 (±11)

24/27

70 (67-72)

68 (66-71)

36/40 906 20/20 80/160 21/21

5.9 (2.1-8.8) 5-10 2 2

76 (65-85) 67 (35-91) 74 (57-85) 76 (±7)

73 (67-82) 66 (31-88) 72 (57-83) 74 (±7)

2 5.9 (2.2-7.9) 3-5

70 (45-81)

Age FB (yrs) Follow-up (yrs)

69 (±8) 66 (40-83) 69 (±8)

67 (±8) 66 (35-81) 69 (±7)

4830/41908 68 37/41

30/31 75/74 28/28 46/48 966/944 25/23

252/255 48/52

Number of Age MB protheses (yrs) (MB/FB) 15/58 70 (45-81)

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

Year

2004 2004 2005 2003 2010 2011 2012 2012 2008 2014 2007 2008

2010 2011 2013 2011 2011 2012 2015 2014 2010 2013 2015 2009

Author

Ranawat [104] Ranawat [105] Rees [106] Saari [107] Sawaguchi [109] Schuster [110] Scuderi [111] Shemshaki [112] Shi [113] Shi [114] Siebold [115] Silvestre [116]

Smith [119] Smith [118] Stoner [120] Tibesku [122] Tibesku [121] Tienboon [123] Tjornild [124] Urwin [125] v/d Bracht [126] v/d Voort [127] van Stralen [128] Vasdev [129]

MA MA CS RCT RCT RCT RCT RCT R SR CS RCT

BiL CS CS RCT CS CS RCT RCT CS CS CS CS 1 1 3 2 2 2 2 2 3 2 3 1

1 3 3 2 3 2 1 1 3 3 3 3

PFC Sigma MB/FB DePuy PFC Sigma MB/FB DePuy TMK knee MB Biomet; AGC Knee FB Biomet Freeman-Samuelson, MB/FB Finsbury PFC Sigma MB/FB DePuy BalanSys MB/FB Mathys Medical NexGen LPS Flex MB/FB PFC Sigma MB/FB DePuy NexGen LPS Flex MB/FB PFC-Sigma MB/FB DePuy Duracon deep-dished MB/FB Howmedica Ceragyr MB Ceraver-Ostéal; Hermes FB Ceraver -Ostéal Multiple Multiple PFC-Sigma MB/FB DePuy Genesis II MB/FB Smith & Nephew Genesis II MB/FB Smith & Nephew PFC Sigma MB/FB DePuy PFC Sigma MB/FB DePuy PFC Sigma MB/FB DePuy Multiple Multiple BalanSys MB/FB Mathys Medical LCS MB DePuy; NexGen FB Zimmer

Study LoE Type of prothesis type

68 (±4) 63 (55-75)

3024/3155 40/38 60/60

67 (±5) 63 (57-76)

66 (47-86) 60 (42-74) 65 (±10) 68 (±10) 66 (56-73) 59 (±9)

71 (±4) 73 (62-79) 70 72 (±8) 63 (35-81) 70 (±12) 70 (42-85) 64 (±3) 66 (52-80) 70 (44-82)

71 (±4) 68 (64-74) 70 67 (±7) 64 (40-80) 68 (±14) 70 (60-83) 63 (±4) 69 (45-81) 68 (54-85)

64 (47-85) 63 (48-79) 66 (±19) 70 (±6) 66 (54-75) 60 (±8)

74 (50-89)

0.5 - 13.2 1 3.5 (1.0-4.6)

2.0 (0.9-3.5) 2 2 2 0.8

3.9 (0.8-5) 2-4 5 6-12 1.3 (±0.5) 6-16 4.7 (4-5)

1.0-1.5 1

18-132

Age FB (yrs) Follow-up (yrs)

74 (50-89)

Age MB (yrs)

1556/1903 910/882 25/17 16/22 16/17 100/100 23/23 8/8

32/95 28/19 150/150 30/26 10/10 17/26 68/68

Number of protheses (MB/FB) 25/25 20/20 7/7 7/15

PART 1 | C H APTE R 3

2001 2005

2012 2011 2009 2012

2012 2013 2004 2011 2008 2013 2014

Vertullo [130] Watanabe [132]

Watanabe [131] Wen [133] Wohlrab [134] Wolterbeek [136]

Wolterbeek [135] Wonglertsiri [137] Woolson [139] Woolson [138] Wylde [141] Zeng [142] Zurcher [143]

RCT CS RCT RCT RCT MA CS

CS MA RCT CS

R BiL

1 3 1 1 1 1 2

2 1 2 3

3 1

Rotaglide MB Corin Medical; NexGen CR FB Zimmer NexGen LPS Flex MB/FB Zimmer Multiple NexGen MB/FB Zimmer Duracon FB Stryker; Triathlon FB/MB Stryker; PFC-Sigma FB DePuy; NexGen MB Zimmer; ROCC MB Biomet Triathlon FB/MB Stryker LPS MB/FB Zimmer LCS MB DePuy; NexGen FB Zimmer LCS MB DePuy; NexGen FB Zimmer Kinemax Plus FB/MB Stryker Multiple NexGen LPS MB/FB Zimmer

Study LoE Type of prothesis type

9/11 103/102 23/29 33/30 108/120 6861 11/10

16/32 1950 19/22 23/29

22/22

1 3 (2.3 - 3.8) 2-6 10 2 1 - 16.8 >1.3

66 (±9) 67 (51-83) 67 (37-83) 78 (56-96) 68 (40-80) 65.3 (±12)

63 (±10) 65 (35-80) 69 (37-83) 78 (48-91) 69 (41-80) 62.8 (±12)

2.0 - 3.4

6.6-8.9

5 0.4-3.6

60 (35-78)

Age FB (yrs) Follow-up (yrs)

60 (35-78)

Number of Age MB protheses (yrs) (MB/FB)

LoE: level of evidence, MA: meta-analysis, SR: systematic review, R: review, RCT: randomised controlled trial, BiL: bilateral study, CS: comparative study. Multiple: More than 6 different types of prostheses were used Data in average (±standard deviation) or average (minimum-maximum)

Year

Author

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

PART 1 | C H APTE R 3

Figure 2. Number of publications per year

Table 2. LoE 1 insert wear results Author

Study Conclusion type

Breugem [18] Kim [67] Kim [68] Smith [118] Smith [119]

RCT BiL BiL MA MA

MB=FB X MB=FB X MB=FB

Radio Thickness Retrieved Retrieved Low- Highlogical measure inserts inserts FB grade grade wear ments MB wear wear MB=FB 2 2 X MB=FB MB=FB

MA: meta-analysis, SR: systematic review, R: review, RCT: randomised controlled trial, BiL: bilateral study, CS: comparative study. MB=FB: no difference between MB-TKA and FB-TKA. MB: results favour MB-TKA. FB: results favour FB-TKA. X: no conclusion because of missing statistical analysis.

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

Table 3. LoE 1 signs of loosening of the prosthesis Author

Study type Conclusion Femoral radiolucencies Aggarwal [1] RCT MB=FB MB=FB Bailey [5] RCT FB MB=FB Bhan [12] BiL MB=FB Cheng [24] MA MB=FB MB=FB Hanusch [43] RCT MB=FB Henricson [46] RCT X X Jolles [58] RCT X MB=FB Kalisvaart [59] RCT MB=FB MB=FB Kim [67] BiL MB=FB MB=FB Kim [66] BiL MB=FB MB=FB Kim [64] BiL MB=FB MB=FB Kim [65] BiL MB=FB MB=FB Kim [68] BiL MB=FB MB=FB Kim [69] RCT MB=FB MB=FB LÃ¤dermann [71] RCT X X Moskal [87] MA MB=FB MB=FB Munro [89] RCT X Nieuwenhuijse [92] RCT MB=FB X Oh [95] MA MB=FB MB=FB Rahman [103] RCT MB=FB MB=FB Scuderi [111] RCT X X Shemshaki [112] RCT MB=FB MB=FB Smith [118] MA X MB=FB Smith [119] MA MB=FB Watanabe [132] BiL MB=FB MB=FB Wen [133] MA MB=FB MB=FB Woolson [139] RCT MB=FB Woolson [138] RCT X MB=FB

Tibial radiolucencies MB=FB FB MB=FB MB=FB

Osteolysis

MB=FB X X MB=FB

MB=FB MB=FB MB=FB X MB=FB X X X X MB=FB

MB=FB MB

MB=FB

MB=FB MB=FB

MB=FB

LoE: level of evidence, MA: meta-analysis, SR: systematic review, R: review, RCT: randomised controlled trial, BiL: bilateral study, CS: comparative study. MB=FB: no difference between MB-TKA and FB-TKA. MB: results favour MB-TKA. FB: results favour FB-TKA. X: no conclusion because of missing statistical analysis

PART 1 | C H APTE R 3

Table 4. LoE 1 survival rate + revisions Author Aggarwal [1] Bailey [5] Bhan [12] Cheng [24] Hanusch [43] Jolles [58] Kalisvaart [59] Kim [68] Kim [64] Kim [65] Kim [66] Kim [67] LÃ¤dermann [71] Moskal [87] Nieuwenhuijse [92] Oh[95] Rahman [103] Scuderi [111] Shemshaki [112] Smith [118] Smith [119] Watanabe [132] Wen [133] Woolson [139] Woolson [138]

Study type RCT RCT BiL MA RCT RCT RCT BiL BiL BiL BiL BiL RCT MA RCT MA RCT RCT RCT MA MA BiL MA RCT RCT

Conclusion MB=FB MB=FB MB=FB MB=FB MB=FB X MB=FB X MB=FB MB=FB MB=FB MB=FB X MB=FB MB=FB MB=FB MB=FB X MB=FB X MB=FB MB=FB MB=FB MB=FB X

Survival rate

MB=FB MB=FB

Revisions MB=FB MB=FB MB=FB

MB=FB MB=FB MB=FB MB=FB X

X MB=FB

MB=FB MB=FB X

Clinical outcome All clinical outcome results can be found in table 5. Overall conclusion of the 50 LoE 1 studies was that there was no difference between MB-TKA and FB-TKA in almost all studies (n=47), with 2 studies reporting results in favour of MB-TKA and 1 study reporting results in favour of FB-TKA. One LoE 2 study and four LoE 3 studies showed clinical outcome results in favour of MB-TKA, opposed to only one that showed more benefits of FB-TKA. However, the other 53 LoE 2 and 3 studies reported no differences (Appendix Table 5).

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

DISCUSSION The most important finding of the present study was an absence in difference between MB-TKA and FB-TKA. When comprehensively reviewing all available literature, type of bearing did not appear to influence insert wear, signs of loosening, survival rate of the prosthesis and clinical outcome. Both the enlarged contact surface and the reduction in movement of the femoral component on the surface of the insert in MB-TKA were hypothesized to result in less polyethylene wear30. The studies with the highest LoE included in this overview did not show differences between MB-TKA and FB-TKA in insert wear. This could be explained by the fact that insert wear is rare altogether and occurs late in the lifecycle of a prosthesis. Since the 15-year survival rate of TKA is known to be above 90%78, only a very small number of patients have revision surgery because of insert wear. With this in mind, studies with large numbers of patients and a very long followup are necessary to be able to determine a difference in insert wear between MB-TKA and FB-TKA. Since in vitro studies also have not been able to produce consistent results on insert wear28, 39, 41, 82, 88, a possible decrease in insert wear does not appear to be an argument in choosing between MB-TKA and FB-TKA. However, when looking at studies included in this overview with a lower LoE, three out of seven LoE 3 studies showed results in favour of MB-TKA. Studies that include retrieved inserts are essential in assessing actual insert wear, but unfortunately this type of research is categorised in a lower LoE and, therefore, often overlooked. The fact that several LoE 3 studies find that MB-TKA appears to be associated with less insert wear is, therefore, noteworthy, but does not seem to be associated with differences in function, outcome or survival. Taking the LoE of studies into account, the current study shows that radiolucencies and osteolysis around MB-TKA do not differ significantly from FB-TKA. The only LoE 1 study that found a higher percentage of tibial radiolucencies in MB-TKA also showed that this difference did not influence clinical outcome in their patients5 and, therefore, this higher percentage seems not to be clinically relevant. It should be noted that the patients in this study were only evaluated at a maximum of 2-year follow-up. Whether the increase in tibial radiolucencies found in their MBTKA group influences revision rates after 10 or 15 years is, therefore, unknown. Several studies mentioned the number of revisions, but did not perform a statistical analysis to evaluate the differences. It was often unclear whether the revisions were caused by aseptic loosening or all causes. The LoE 1 studies did not show differences in the number of revisions. It is worth mentioning that three studies with a LoE of 2 or 3 showed a lower survival rate for MB-TKA compared to FB-TKA.

PART 1 | C H APTE R 3

Table 5. LoE 1 Clinical outcome parameters Author

Study type Aggarwal [1] RCT Bailey [5] RCT Ball [6] RCT Beard [10] BiL Bhan [12] BiL Breugem [18] RCT Cheng [24] MA Chiu [25] BiL Ferguson [36] RCT Hansson [42] RCT Hanusch [43] RCT Hasegawa [45] BiL Henricson [46] RCT Jawed [57] BiL Jolles [58] RCT Kalisvaart [59] RCT Kim [67] BiL Kim [61] RCT Kim [69] RCT Kim [64] BiL Kim [60] RCT Kim [65] BiL Kim [68] BiL Kim [66] BiL LÃ¤dermann [71] RCT Lampe [72] RCT Lizaur [75] RCT Marques [80] RCT Matsuda [81] RCT Minoda [85] RCT Moskal [87] MA Munro [89] RCT Nieuwenhuijse [92] RCT Nutton [93] RCT Oh [95] MA Okamoto [96] RCT Price [101] BiL Rahman [103] RCT Ranawat [104] BiL Scuderi [111] RCT

Conclusion

Questionnaire VAS

Flexion Extension Preference

MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB X MB=FB MB=FB FB MB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB X MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB MB=FB MB=FB MB=FB

MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB MB=FB MB=FB MB=FB

MB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB

MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB

MB=FB

MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB MB=FB MB=FB

FB X

MB=FB MB=FB MB=FB

MB=FB MB=FB MB=FB MB=FB

MB=FB MB=FB MB=FB

MB=FB

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

Table 5. Continued Author Study type Shemshaki [112] RCT Smith [118] MA Smith [119] MA Vasdev [129] RCT Watanabe [132] BiL Wen [133] MA Wolterbeek [135] RCT Woolson [139] RCT Woolson [138] RCT Wylde [141] RCT

Conclusion

Questionnaire VAS

MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB

Flexion Extension Preference

MB=FB MB=FB X MB=FB MB=FB X MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB

MB=FB

In this literature overview patient reported outcomes of questionnaires were included to quantify clinical outcome. The included literature showed that the experienced clinical outcome after undergoing MB-TKA did not differ from patients who underwent FB-TKA. The pain scores and ranges of motion of the knee also did not differ between both types of bearing. Besides, it has been shown that differences found in range of motion and questionnaires are hard to translate to clinically important differences, since these differences can fall within the variation of normal range of knee motion105. Furthermore, differences in objective measurements, like range of motion, do not appear to relate directly to the subjectively experienced quality of movement115. Based on this reasoning, in combination with the high amount of studies that did not find any differences in both the questionnaire results and the range of motion between MB-TKA and FB-TKA, it can be concluded that there is no difference between MB-TKA and FB-TKA in clinical outcome. A strength of the current literature overview is the large number of included studies. In the first Cochrane review on this subject in 2004, only 2 articles were of sufficient methodological quality to be included55. Scientific research on MBTKA has increased dramatically after this review, and out of the 127 studies included in the current study, 51 were LoE 1. The present paper provides an overview of both high and lower LoE studies that has not been presented earlier. Another strength is the fact that results were included on four different theorized

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advantages of MB-TKA, and, therefore, a more complete picture of the results of MB-TKA in comparison with FB-TKA is given. There are also several limitations to the current study. Included studies were categorised according to their level of evidence108, 117, 140. Although this method has proven reliable and has been widely accepted for classifying methodological designs13, 94, this classification does not fully address the methodological quality99. The results of several studies have been included twice, since several RCT and CS studies that were included are also used in the SR and MA studies. It is possible that a small number of studies have not been included because only the PubMed database was searched. However, the chance that these studies would alter the conclusions of this study is small, considering the large amount of included studies and their comparable results. It can be considered a limitation that all different brands of prostheses and the different types (e.g. posterior stabilised/cruciate retaining) in MB-TKA and FB-TKA groups were combined. Because of this heterogeneity, it is possible that better outcome of individual prostheses is not fully addressed. This is inherent to the design of this literature overview and to (systematic) literature reviews in general. Based on the consensus amongst LoE 1 studies it is not to be expected that further differentiation into different types of prostheses would change the conclusions of this literature overview. The number of studies published on MB-TKA and FB-TKA is large and still increasing. However, the recent increase in evidence does not seem to provide new insights. It can, therefore, be argued that the discussion concerning the differences between MBTKA and FB-TKA is not furthered by additional studies on this subject.

CONCLUSION An extensive literature review was performed on studies examining differences between MB-TKA and FB-TKA, including a large number of studies with a lower LoE that are generally overlooked in other reviews. No clear differences were found between MB-TKA and FB-TKA in insert wear, signs of loosening of the prosthesis, survival rate and clinical outcome. Because of this, surgeons deciding between MB-TKA and FB-TKA for use in their day-to-day practice should be guided by different arguments, like surgeon experience with a certain type of prosthesis and financial or logistic advantages of different prostheses.

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

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N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

123. Tienboon P, Jaruwangsanti N, Laohasinnurak P (2012) A prospective study comparing mobilebearing versus fixed-bearing type in total knee arthroplasty using the free-hand-cutting technique. J Med Assoc Thai 95:S77-S86 124. TjĂ¸rnild M, SĂ¸balle K, Hansen PM, Holm C, Stilling M (2015) Mobile- vs. fixed-bearing total knee replacement. Acta Orthop 86:208-214 125. Urwin SG, Kader DF, Caplan N, St Clair Gibson A, Stewart S (2014) Gait analysis of fixed bearing and mobile bearing total knee prostheses during walking: do mobile bearings offer functional advantages? Knee 21:391-395 126. Van der Bracht H, Van Maele G, Verdonk P, Almqvist KF, Verdonk R, Freeman M (2010) Is there any superiority in the clinical outcome of mobile-bearing knee prosthesis designs compared to fixed-bearing total knee prosthesis designs in the treatment of osteoarthritis of the knee joint? A review of the literature. Knee Surg Sports Traumatol Arthrosc 18:367-374 127. van der Voort P, Pijls BG, Nouta KA, Valstar ER, Jacobs WC, Nelissen RG (2013) A systematic review and meta-regression of mobile-bearing versus fixed-bearing total knee replacement in 41 studies. Bone Joint J 95-B:1209-1216 128. van Stralen RA, Heesterbeek PJ, Wymenga AB (2015) Different femorotibial contact points between fixed- and mobile-bearing TKAs do not show clinical impact. Knee Surg Sports Traumatol Arthrosc 23:3368-3374 129. Vasdev A, Kumar S, Chadha G, Mandal SP (2009) Fixed- versus mobile-bearing total knee arthroplasty in Indian patients. J Orthop Surg (HongKong) 17:179-182 130. Vertullo CJ, Easley ME, Scott WN, Insall JN (2001) Mobile bearings in primary knee arthroplasty. J Am Acad Orthop Surg 9:355-364 131. Watanabe T, Ishizuki M, Muneta T, Banks SA (2012) Matched comparison of kinematics in knees with mild and severe varus deformity using fixed- and mobile-bearing total knee arthroplasty. Clin Biomech (Bristol, Avon) 27:924-928 132. Watanabe T, Tomita T, Fujii M, Hashimoto J, Sugamoto K, Yoshikawa H (2005) Comparison between mobile-bearing and fixed-bearing knees in bilateral total knee replacements. Int Orthop 29:179-181 133. Wen Y, Liu D, Huang Y, Li B (2011) A meta-analysis of the fixed-bearing and mobile-bearing prostheses in total knee arthroplasty. Arch Orthop Trauma Surg 131:1341-1350 134. Wohlrab D, Hube R, Zeh A, Hein W (2009) Clinical and radiological results of high flex total knee arthroplasty: a 5 year follow-up. Arch Orthop Trauma Surg 129:21-24 135. Wolterbeek N, Garling EH, Mertens BJ, Nelissen RG, Valstar ER (2012) Kinematics and early migration in single-radius mobile- and fixed-bearing total knee prostheses. Clin Biomech (Bristol, Avon) 27:398-402 136. Wolterbeek N, Nelissen RGHH, Valstar ER (2012) No differences in in vivo kinematics between six different types of knee prostheses. Knee Surg Sports Traumatol Arthrosc 20:559-564 137. Wonglertsiri S, Uthaicharatratsame C (2013) Comparison of fixed bearing and mobile bearing total knee arthroplasty using identical femoral component. J Med Assoc Thai 96:203-208 138. Woolson ST, Epstein NJ, Huddleston JI (2011) Long-term comparison of mobile-bearing vs fixedbearing total knee arthroplasty. J Arthroplasty 26:1219-1223 139. Woolson ST, Northrop GD (2004) Mobile- vs. fixed-bearing total knee arthroplasty: a clinical and radiologic study. J Arthroplasty 19:135-140 140. Wright JG, Swiontkowski MF, Heckman JD (2003) Introducing levels of evidence to the journal. J Bone Joint Surg Am 85-A:1-3 141. Wylde V, Learmonth I, Potter A, Bettinson K, Lingard E (2008) Patient-reported outcomes after fixed- versus mobile-bearing total knee replacement: a multi-centre randomised controlled trial using the Kinemax total knee replacement. J Bone Joint Surg Br 90:1172-1179 142. Zeng Y, Shen B, Yang J, Zhou ZK, Kang PD, Pei FX (2013) Is there reduced polyethylene wear and longer survival when using a mobile-bearing design in total knee replacement? A metaanalysis of randomised and non-randomised controlled trials. Bone Joint J 95-B:1057-1063 143. Zurcher AW, van Hutten K, Harlaar J, Terwee CB, Rob Albers GH, Poll RG (2014) Mobile-bearing total knee arthroplasty: More rotation is evident during more demanding tasks. Knee 21:960-963

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APPENDICES Appendix Table 1 . Searchstring for PubMed/MEDLINE 1. Search rotating platform 2. Search meniscal bearing 3. Search anterior-posterior glide-rotation 4. Search mobile bearing 5. Search (1 or 2 or 3 or 4) 6. Search total or TKA 7. Search fixed 8. Search (5 and 6 and 7) 9. Search hemi 10. Search unicompartmental 11. Search (9 or 10) 12. Search 8 not 11 Filters: Abstract; English

Appendix Table 2. LoE 2+3 insert wear results Author

Aglietti [2] Mahoney [79] Pijls [98] Berry [11] Biau [14] Engh [33] Ho [48] Huang [52] Lu [76] Stoner [120]

Study LoE Conclu Radiolo Thickness type sion gical measure wear ments RCT 2 MB=FB MB=FB RCT 2 X RCT CS CS CS CS CS CS CS

2 3 3 3 3 3 3 3

MB=FB MB MB=FB MB=FB MB MB MB=FB MB=FB

Retrieved Retrieved Lowinserts inserts grade MB FB wear

Highgrade wear

218

MB=FB

12 15 34 15 25

12 36 37 22 17

MB=FB MB=FB MB=FB

MB=FB

MB MB MB=FB MB=FB

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

Appendix Table 3. LoE 2+3 signs of loosening of the prosthesis Author Aglietti [2] Bistolfi [15] Bo [16] Breeman [17] Harrington [44] Hofstede [49] Jacobs [56] Li [73] Mahoney [79] Namba [90] Pijls [98] Radetzki [102] v/d Voort [127] Wohlrab [134] Zeng [142] Argenson [4] Huang [50] Huang [53] Huang [52] Kim [63] Minoda [84] Post [100]

Study type RCT CS MA RCT RCT SR RCT MA RCT CS RCT RCT SR RCT MA CS R CS CS CS CS R

LoE Conclusion 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3

MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB X MB=FB MB=FB X FB X MB=FB MB=FB MB=FB

Femoral radiolucencies MB=FB X MB=FB MB=FB MB=FB MB=FB MB=FB

X X MB=FB X MB=FB

Tibial Osteolysis radiolucencies X MB=FB

MB=FB MB=FB

X X MB=FB

MB=FB

MB=FB X

MB=FB MB=FB X

MB=FB

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Appendix Table 4. LoE 2+3 survival rate + revisions Author Aglietti [2] Bistolfi [15] Bo [16] Breeman [17] Harrington [44]

Hofstede [49] Jacobs [56]

Mahoney [79] McGonagle [83] Namba [90] Pijls [98] Radetzki [102]

v/d Voort [127] Wohlrab [134]

Zeng [142] Argenson [4] Gothesen [38] Gupta [40]

Huang [50] Huang [53] Huang [52] Kim [63] Minoda [84]

Post [100]

Study type RCT CS MA RCT RCT SR RCT RCT CS CS RCT RCT SR RCT MA CS CS CS R CS CS CS CS R

LoE 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3

Conclusion

Survival rate

Revisions

MB=FB

X MB=FB MB=FB

MB=FB

MB=FB MB=FB MB=FB

MB=FB MB=FB

FB MB=FB MB=FB MB=FB

MB=FB FB X X MB=FB

MB=FB MB=FB

FB X FB X MB=FB

MB=FB MB=FB FB

FB X X X

MB=FB

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

Appendix Table 5. LoE 2+3 Clinical outcome parameters Author Aglietti [2] Bistolfi [15] Bo [16] Breeman [17] Breugem [19] Delport [26] Harrington [44] Higuchi [47] Hofstede [49] Jacobs [55] Jacobs [56] Kotani [70] Li [73] Mahoney [79] McGonagle [83] Pagnano [97] Pijls [98] Radetzki [102] Saari [107] Schuster [110] Tibesku [122] Tibesku [121] Tjornild [124] Urwin [125] v/d Voort [127] Watanabe [131] Wohlrab [134] Zurcher [143] Argenson [4] Banks [7] Banks [8] Banks [9] Biau [14] Catani [22] Chen [23] Delport [27] Dennis [29] Dennis [31] Dennis [32] Evans [34] Geiger [37]

Study type RCT CS MA RCT RCT CS RCT RCT SR SR RCT CS MA RCT CS RCT RCT RCT RCT CS RCT RCT RCT RCT SR CS RCT CS CS CS CS CS CS CS CS CS R CS CS CS CS

LoE 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3

Conclusion Question naire MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB MB FB X X MB=FB MB=FB X X MB=FB MB=FB MB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB

VAS

Flexion

Extension Preference

FB MB=FB MB=FB

MB=FB

MB=FB MB=FB MB=FB MB MB=FB MB=FB MB=FB MB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB

MB MB=FB

MB=FB MB=FB MB=FB

MB=FB MB=FB MB=FB MB=FB MB MB=FB MB=FB MB=FB FB

MB=FB MB MB

MB=FB

MB=FB MB=FB MB=FB

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Appendix Table 5. Conclusion Author

Study type Kim [63] CS Kim [62] CS Liu [74] CS Luring [77] CS Minoda [84] CS Post [100] R Ranawat [105] CS Rees [106] CS Sawaguchi [109] CS Shi [114] CS Shi [113] CS Siebold [115] CS Silvestre [116] CS Tienboon [123] RCT v/d Bracht [126] R van Stralen [128] CS Wolterbeek [135] CS Wonglertsiri [137] CS

LoE 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3

Conclusion Question naire MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB X MB=FB MB MB MB=FB X MB=FB X MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB MB=FB X MB=FB MB=FB

VAS

Flexion

Extension Preference

MB=FB MB=FB MB=FB MB=FB

MB=FB

MB=FB MB=FB MB=FB MB=FB MB X MB=FB MB=FB MB=FB MB=FB

MB=FB

N O DI FFERENCES BETWEEN FIXED - AND MOBILE-BEARING TKA

CHAPTER 4 Does insert type affect clinical and functional outcome in total knee arthroplasty? A randomised controlled clinical trial with 5-year follow-up

Journal of Arthroplasty. 2015 Nov;30(11):1931-7. BL Fransen, MJM Hoozemans, LCM Keijser, ME van Lent, CCPM Verheyen, BJ Burger

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ABSTRACT New insert types have been developed to improve clinical and functional outcome in both mobile bearing (MB-TKA) and fixed bearing total knee arthroplasty (FBTKA). A prospective single blinded randomised controlled clinical trial was performed to evaluate 2 types of MB-TKA inserts and 2 types of FB-TKA inserts of the Genesis II prosthesis (Smith & Nephew) in 146 patients with 5-years followup. A significant difference (p=0.042) between the MB-TKA inserts was found in KSS function scores, but clinical significance is expected to be limited. Goniometry, temporal gait parameters and QoL were similar in all groups. Survival was significantly better (p=0.047) for FB-TKA. The comparable outcome and higher revision rate in MB-TKA indicate that FB-TKA may be preferential for the Genesis II implant system.

D OES INSERT TYPE AFFECT OUTCOME IN TKA?

INTRODUCTION Total knee arthroplasty (TKA) has been increasingly performed to treat patients with osteoarthritis of the knee. The number of TKA procedures is expected to rise more as patients become older and remain active longer1,2. The original total knee prostheses were developed with an insert fixed to the tibial component (fixed bearing (FB)) and allowed only minimal tibial axial rotation, which is normally present in knee motion during flexion and extension3. In the 1980â&#x20AC;&#x2122;s mobile bearing (MB) TKA was developed to allow more axial rotation of the insert relative to the tibia4. MB-TKA is assumed to cause less wear of the insert, associated with less loosening and revisions, and provide a more natural movement of the knee joint3-5. So far, studies have not been able to prove these theoretical advantages, with similar results in FB-TKA and MB-TKA when looking at in vivo kinematics3,5,6, clinical function7-10, quality of life (QoL)7, radiological outcome6,11 and gait parameters12,13. To further improve MB-TKA, inserts have been developed with anterior-posterior translation as well as axial rotation. These rotating & translating inserts are hypothesised to allow more femoral condylar rollback14. For the FB-TKA, a new deep dish insert was developed to reduce the need for resection of the femoral bone compared to the normal dish insert15-17. To our knowledge, there have been no comparative studies with medium to long term follow-up of the outcome of both FB-TKA and MB-TKA in general and insert type more specifically. The aim of this study was to compare clinical and functional outcomes up to 5 years after FB-TKA and MB-TKA, in a randomized controlled clinical trial in a population of patients with osteoarthritis of the knee who were scheduled to undergo total knee replacement. In addition, to explore the effect of insert type, outcomes of Normal Dish (ND) and Deep Dish (DD) inserts for FB-TKA were compared in a randomized design as well as Rotating (R) and Rotating/Translating (R/T) inserts for MB-TKA.

PATIENTS AND METHODS Study Design A multicenter, prospective, randomised, single blinded parallel-group clinical study was conducted in 2 large teaching hospitals in the Netherlands with an allocation ratio of 1:1:1:1. After inclusion, patients were first randomly assigned to either the fixed bearing (FB) or the mobile bearing (MB) group. Further randomisation was done within each group to either a normal dish (ND) insert or

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deep dish (DD) insert in the FB group, or to either a rotating (R) or rotating/ translating (R/T) insert in the MB group. This study was performed in accordance with the guidelines on Good Clinical Practice of the International Conference on Harmonisation18, and the Declaration of Helsinki19. The study protocol was approved by the Medical Ethical Committee at Zwolle, The Netherlands and registered under number 01.0319. Study Population The study took place in two Dutch high volume general teaching hospitals between January 2002 and December 2011. Patients aged 50 to 75 years with osteoarthritis for whom a cemented TKA was indicated were eligible for inclusion. Inclusion and exclusion criteria are detailed in Table 1. Recruitment took place at the orthopaedic outpatient clinic in both hospitals and was done by the attending orthopaedic surgeons. Table 1. Inclusion and exclusion criteria Inclusion criteria - Diagnosis of osteoarthritis of the involved knee - Patients of either gender requiring cemented total knee replacement surgery - Adults ranging in age from 50-75 years inclusive at moment of inclusion - Patients have to be free of or treated for cardiac, pulmonary, haematological or other conditions that would pose excessive operative risk - Adults able to understand their role as participants in a clinical study, who agree to return for follow-up, are willing to follow instructions and who agree to provide Informed Consent in accordance with the Medical Ethical Review Committee Requirements Exclusion criteria - Diagnosis of rheumatoid arthritis - Insufficient quantity or quality of bone support, resulting from conditions such as cancer, distal femoral/proximal tibial osteotomy, osteoporosis or metabolic disorders of calcified tissues - Revision of previous knee arthroplasty or arthrodesis - Pre-existing local knee sepsis - Pre-existing neurologic disorder - Patients unable or unwilling to comply with all the aspects of the study, return for scheduled follow-up through at least five years, or adhere to all applicable conditions of the study protocol - Genu varus > 25 degrees - Genu valgus > 10 degrees - Collateral ligament or PCL insufficiency

D OES INSERT TYPE AFFECT OUTCOME IN TKA?

Intervention All patients received a cruciate retaining Genesis II Total Knee Replacement prosthesis with cemented tibial and femoral components with a standard polyethylene insert (Smith & Nephew, London, United Kingdom) 17,20-22. The bearing and insert as allocated through randomisation were implanted. Eight orthopaedic surgeons were involved in the study. All eight surgeons implanted all four insert types using the surgical technique for TKA with which they were most comfortable. No minimal invasive incisions were used. A patellar component was placed when the operating surgeon deemed this necessary. No patients underwent a bilateral TKA in a single session. Mobilisation after surgery was identical for all groups and consisted of walking with 2 crutches for 6 weeks, followed by 1 crutch for another 4 weeks. During this time all patients received physical therapy by a blinded therapist. Study follow-up visits were at 1 year and 5 years after surgery. Primary outcome parameters Primary outcome parameters were knee function and walking ability as measured using the Knee Society Clinical Rating Scale (KSS) as described by Insall et al. in 198923. The KSS is divided in two subscales: a knee rating assessing the function of the joint (0 being the worst score and 100 a perfect score), and a functional rating of the patientsâ&#x20AC;&#x2122; ability to walk and climb stairs (0 indicating an inability to walk and 100 indicating unimpaired movement)23. KSS forms were filled in before surgery and at 1 year and 5 years. Secondary outcome parameters Gait parameters Gait analyses were performed at baseline and at 1 and 5 years follow-up using the Computer Dyno Graphy (CDG) system (Infotronic, Geesteren, The Netherlands), which consists of 2 measuring soles with 8 sensors per foot. The CDG system was extended with a goniometry system to assess the knee angles during walking. Patients were instructed to take consecutive steps at their preferred walking speed for at least 20 seconds. Foot sensor and goniometry signals were sampled at a frequency of 50 Hz and stored in a data logging device attached on the patient. Custom-made computer software was used for analysis of the data. For the analyses, the time series of knee angles were normalized to 100 time points for each step (heel strike to heel strike) and the average of the 100 time points of the steps within the 20-30 second trial for each participant was

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calculated. Of this averaged step of each participant, the maximum flexion during the stance phase (Max-stance) and the maximum flexion during the swing phase (Max-swing) of the affected leg were analysed. Temporal gait parameters assessed were the single support time of the affected leg and the ratio of the single support time of the affected and contra-lateral leg. The measurements were normalised and averaged using the same procedure as described above for knee motion. Quality of Life QoL was measured using the validated Dutch version of the SF-12 Health Survey24 before surgery and at 1 and 5 years follow-up. The SF-12 is subdivided into a physical and mental score, which were analysed separately. Revisions and manipulations Revision was defined as a surgical procedure that replaced or removed one or more components of the implant. Manipulations because of a flexion deficit performed under anaesthesia were also registered. Randomisation and blinding Randomisation was computer generated with a block size of 1:4. The allocation was concealed by one of the researchers in an envelope, which was opened in the operation room at the start of the procedure. Patients were blinded for the duration of the study. Baseline measurements were performed by a blinded researcher. Due to logistical reasons it was not possible to assure that all follow-up measurements were done by a blinded researcher. Statistical Methods Independent t-tests or their non-parametric equivalent were performed on all patient characteristics and in the dropout analysis for normally distributed and not-normally distributed data, respectively. To determine whether continuous outcome measures changed differently over time (from baseline to one and five year follow-up) between FB-TKA and MB-TKA groups, as well as the insert types groups within each bearing group, two-way mixed design ANOVA’s were performed. One-way within- and between-subjects ANOVAs with Bonferroni correction were used to examine the interaction effect if significant and to calculate the 95% CI for each difference between the means. Homogeneity of variance was checked using Levene’s test. The assumption of sphericity was checked according to Girden25. If the Greenhouse-Geisser epsilon was ≥ 0.75, the Huynh-Feldt correction was used, otherwise the Greenhouse-Geisser correction was used.

D OES INSERT TYPE AFFECT OUTCOME IN TKA?

Categorical outcome measures were analysed using Chi-squared tests. KaplanMeier survival analyses were performed for both revisions and manipulations for bearing types as well as insert types, with additional log-rank tests (Mantel-Cox) to determine whether the Kaplan-Meier curves were significantly different. A p<0.05 was considered significant. All analyses were performed with IBM SPSS Statistics version 20 (IBM Corporation, Armonk, NY, USA).

RESULTS Study population Patients were recruited between February 2002 and June 2006, and follow-up measurements took place between February 2003 and October 2011: preoperative, one and five years postoperative. Out of the 251 patients who were assessed for eligibility, 237 patients were included for randomisation (Figure 1). There were nine randomisation violations: four violations were because of missing randomisation envelopes during surgery, two violations were because of anatomical characteristics (tight ligaments and an imbalance between femur and tibia) of the patient, one violation was because of inexperience of the surgeon with the allocated type of insert at that time and of two patients the reason for the protocol violation was not known. A per protocol analysis was performed, meaning that patients that did not receive the insert that was allocated in randomisation were analysed according to the insert that was placed during surgery. Patients who underwent a revision were excluded from analysis after the revision procedure, except for 1 patient who underwent a revision of the insert within 2 weeks after the primary surgery and was able to follow the normal study protocol. Patient characteristics at baseline are shown in Table 2. A total of 146 patients (61.6%) were able to complete the entire study protocol. Drop-out analysis showed that patients who did not complete the entire protocol were comparable in all baseline characteristics and measurements to the group of patients that were included in the final analyses (Table 3).

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Figure 1. CONSORT diagram with participant flow35. Patients that had a randomisation violation were analysed according to the insert implanted during surgery.

Primary outcome parameters Before surgery there were no significant differences in the knee score or functional score of the KSS between the bearing groups or between the ND-DD and R-R/T insert groups. The results in both scores were comparable when looking at the FB and MB groups and at the ND and DD groups. There was a significant interaction between the R and R/T group and time in function score, which seemed most likely to be caused by a relatively low score in the R group at 5 year follow-up. Further analysis using a Studentâ&#x20AC;&#x2122;s T-test showed no significant difference between the R and R/T group in KSS function score at 5 years follow-up (p=0.066, 95%CI -23.9 â&#x20AC;&#x201C; 0.80) The knee score changed comparably for both types of MB insert (Table 4).

D OES INSERT TYPE AFFECT OUTCOME IN TKA?

Table 2. Baseline characteristics & surgical parameters Age at time of surgery (years) Gender Female Male BMI Side Left Right Type of anesthesia Spinal General Epidural Operation time (minutes)

Age at time of surgery (years) Gender Female Male BMI Side Left Right Type of anesthesia Spinal General Epidural Operation time (minutes)

Fixed Bearing (n=123) 65.8 (50 - 76)

Mobile Bearing (n=114) 65.7 (52 - 76)

88 (71.5%) 35 (28.5%) 30.2 (21.7 – 44.1)

77 (67.5%) 37 (32.5%) 30.2 (22.0 – 43.3)

66 (53.7%) 57 (46.3%)

60 (52.6%) 54 (47.4%)

87 (70.7%) 35 (28.5%) 1 (0.8%) 72.0 (45 - 134)

89 (78.1%) 23 (20.2%) 2 (1.7%) 75.4 (40 - 180)

Normal Dish (n=64)

Deep Dish (n=59)

Rotating (n=58)

66.1 (52 - 75)

65.4 (50 - 76)

65.5 (52 - 75)

Rotating/ Translating (n=56) 66.0 (55 - 76)

51 (79.7%) 37 (62.7%) 40 (69.0%) 37 (66.1%) 13 (20.3%) 22 (37.3%) 18 (31.0%) 19 (33.9%) 30.4 (21.7 – 44.1) 30.1 (22.0 – 43.2) 29.9 (22.0 – 41.1) 30.5 (22.0 – 43.3) 38 (59.4%) 26 (40.6%)

28 (47.5%) 31 (52.5%)

31 (53.5%) 27 (46.5%)

29 (51.8%) 27 (48.2%)

43 (67.2%) 20 (31.3%) 1 (1.5%) 70.8 (45 - 102)

44 (74.6%) 15 (25.4%) 0 (0%) 73.2 (45 - 134)

42 (72.4%) 15 (25.9%) 1 (1.7%) 72.9 (40 - 120)

47 (83.9%) 8 (14.3%) 1 (1.8%) 77.8 (50 - 180)

Data in Mean (range) or Number (%) BMI = Body Mass Index

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Table 3. Dropout analysis showed no significant differences between the patients who completed the entire protocol and dropout patients Age at time of surgery (years) Gender: Female Male BMI Side: Left Right Type of anesthesia: Spinal General Epidural OK time (minutes) Randomisation Bearing FB MB Insert ND DD R R/T Baseline measurements KSS Knee Score Function Score Goniometry (degrees) Max Stance Max Swing Temporal gait parameters (seconds) Single stance affected leg Ratio single stance SF-12 Function score Mental score

Completed protocol (n=146) 65.8 (52 – 76)

Dropout (n=91)

p-value

65.7 (50 - 75)

0.956 0.633

100 (68.5%) 46 (31.5%) 30.6 (22.0 – 42.6)

65 (71.4%) 26 (28.6%) 29.5 (21.7 – 44.1)

73 (50%) 73 (50%)

53 (58.2%) 38 (41.8%)

0.083 0.216

0.069 112 (76.7%) 34 (23.3%) 0 (0%) 72.0 (45 - 135)

64 (70.3%) 24 (26.4%) 3 (3.3%) 76.3 (40 - 180)

77 (52.7%) 69 (47.3%)

46 (50.6%) 45 (49.4%)

39 (26.7%) 38 (26.0%) 36 (24.7%) 33 (22.6%)

25 (27.5%) 21 (23.0%) 22 (24.2%) 23 (25.3%)

48.4 (0 - 90) 43.3 (5 – 100)

49.2 (3 – 93) 44.0 (0 - 100)

0.792 0.777

9.2 (-5.5 – 26.6) 43.7 (1.8 – 74.1)

9.1 (-2.1 – 25.9) 46.1 (21.2 – 78.7)

0.900 0.158

0.071 0.743

0.944

0.418 (0.26 – 0.67) 0.413 (0.31 – 0.53) 0.552 0.989 (0.54 – 1.64) 0.969 (0.69 – 1.23) 0.263 33.2 (16.5 – 55.1) 53.9 (23.2 – 68.3)

33.6 (20.9 – 52.8) 52.4 (18.6 – 71.8)

0.691 0.300

Data in Mean (ranges) or Number (%) BMI = Body Mass Index; FB = Fixed Bearing; MB = Mobile Bearing; ND = Normal Dish; DD = Deep Dish; R = rotating; R/T = rotating & translating; KSS = Knee Society Score

D OES INSERT TYPE AFFECT OUTCOME IN TKA?

Secondary outcome parameters Gait parameters The change in maximum knee flexion over time during the stance phase did not differ between any of the groups, and all of the groups had less than 2 degrees average improvement (Table 4). The maximum flexion during swing phase also did not show any differences between either the bearing or insert groups. Temporal gait parameters were the single support time of the affected leg and the ratio of the single support time of the affected and contralateral leg (Table 4). The measurements of single support time of the affected leg and the ratio were comparable in all groups. Quality of Life Differences between groups were not different for the three time points for either the function scores or the mental scores of the SF-12 questionnaire. The mental scores showed minimal difference between baseline and the follow-up measurements (Table 4). Revisions and manipulations There was one revision in the FB group, where the ND-insert was replaced because of an infection within two weeks after surgery. Six patients in the MB group underwent a revision, of whom four had a R/T insert. Of these six revisions 2 patients had loosening of the tibial component, 2 had a limited range of motion, 1 had an insert screw that had loosened, and 1 patient had an infection. All revisions occurred within the first year after the initial surgery. Survivorship analyses showed a survival of 99.2% and 94.7% for FB-TKA and MB-TKA respectively (Table 5). Time to revision because of any reason over time as evaluated using KaplanMeier curves was significantly different (p=0.047) (Figure 2). When considering only revision because of mechanical loosening the log-rank test was not significant (p=0.142). Also, when looking at the different insert types no significant difference in time to revision over time was found (p=0.133). Kaplan-Meier analysis of time to manipulations did not show significant differences for either bearing type (p=0.209) or insert type (p=0.066), apart from the R/T insert which appeared to have a greater manipulation rate (p=0.051).

8.7 (-5.5 – 26.6) 41.9 (1.8 – 74.0)

45.4 (6.5 – 74.1)

48.9 (4.5 – 75.4)

11.2 (1.3 – 28.9)

82.6 (5 - 100)

90.9 (56 – 100)

1 year follow-up

47.8 (29.0 - 62.7)

10.6 (1.3 – 20.7)

79.9 (25 - 100)

91.0 (54 – 100)

45.6 (18.6 – 64.1)

10.2 (1.7 – 20.0)

78.6 (20 - 100)

91.7 (55 - 100)

5 years follow-up

46.1 (20.0 – 66.6)

9.6 (0.7 – 21.7)

75.4 (0 - 100)

91.4 (31 – 100)

0.171

0.917

0.864

0.962

p-value

43.7 (5 – 70)

Function score

44.4 (6.5 – 66.2)

Max Swing

46.8 (22.3 – 74.1)

9.7 (1.5 – 26.5)

44.5 (5 – 80)

49.5 (21 – 74)

54.8 (23.2 – 68.3)

30.3 (0.0 – 50.8)

1.01 (0.54 – 1.40)

49.4 (9.4 – 70.5)

10.9 (1.5 – 27.0)

80.7 (5 - 100)

88.7 (56 – 100)

1 year follow-up

52.5 (33.2 – 65.8)

42.0 (19.5 – 56.2)

1.02 (0.81 – 1.49)

48.5 (4.5 – 75.4)

11.4 (1.3 – 28.9)

84.7 (15 – 100)

93.2 (75 – 100)

54.9 (33.2 – 63.5)

43.5 (17.3 – 56.6)

1.01 (0.78 – 1.68)

45.4 (22.8 – 64.1)

10.3 (1.7 – 20.0)

77.8 (20 – 100)

90.7 (59 – 100)

5 years follow-up

52.3 (31.5 – 66.8)

42.9 (18.7 – 61.0)

1.01 (0.69 – 1.15)

45.8 (18.6 – 59.7)

10.0 (3.7 – 18.3)

79.4 (35 – 100)

92.8 (55 – 100)

54.9 (33.7 – 65.6)

43.3 (17.1 – 59.7)

1.00 (0.82 – 1.52)

0.581

0.823

0.783

0.692

p-value

0.536

0.122

0.086

33.0 (20.1 – 55.1)

56.0 (36.8 – 65.9)

Mental score

0.95 (0.00 – 1.64)

Function score

SF-12

Ratio single stance

51.4 (33.5 – 65.3)

32.5 (20.4 – 50.8)

0.97 (0.56 – 1.32)

54.0 (36.4 – 65.8)

44.1 (26.3 – 56.2)

1.02 (0.81 – 1.49)

51.0 (33.2 – 63.3)

39.9 (19.5 – 56.2)

1.03 (0.81 – 1.23)

55.1 (35.0 – 66.8)

45.0 (18.7 – 58.9)

0.99 (0.69 – 1.12)

49.4 (31.5 – 62.1)

40.6 (20.9 – 61.0)

1.03 (0.82 – 1.15)

0.421

0.186

0.822

Single stance affected leg 0.407 (0.00 – 0.52) 0.413 (0.26 – 0.57) 0.404 (0.00 – 0.51) 0.400 (0.00 – 0.58) 0.409 (0.30 – 0.57) 0.431 (0.37 – 0.63) 0.464

Temporal gait parameters

9.6 (-0.6 – 20.8)

Max Stance

Goniometry

47.4 (14 – 78)

Knee score

KSS

Baseline

53.8 (33.5 – 65.9)

32.8 (20.1 – 55.1)

Mental score

0.96 (0.00 – 1.64)

Function score

SF-12

Ratio single stance

Single stance affected leg 0.410 (0.00 – 0.57) 0.420 (0.30 – 0.67) 0.402 (0.00 – 0.58) 0.406 (0.30 – 0.72) 0.420 (0.30 – 0.63) 0.403 (0.30 – 0.52) 0.110

Temporal gait parameters

Max Swing

Max Stance

42.9 (5 - 100)

48.7 (0 – 90)

9.7 (-0.6 – 26.5)

44.1 (5 - 80)

Function score

Goniometry

48.5 (14 - 78)

Knee score

KSS

Baseline

Table 4. Primary and secondary outcome parameters

PART 1 | C H APTE R 4

44.9 (10 - 100)

Function score

41.4 (4.7 – 57.5)

Max Swing

42.5 (1.8 – 74.0)

9.1 (-0.3 – 24.6)

40.8 (5 – 90)

46.5 (0 – 90)

R/T

47.2 (29.0 – 60.7)

10.3 (1.3 – 19.7)

80.1 (25 - 100)

92.2 (61 – 100)

1 year follow-up

48.3 (34.1 – 62.7)

10.9 (4.0 – 20.7)

79.7 (30 - 100)

89.6 (54 – 99)

R/T

R/T 94.0 (78 – 99) 81.4 (0 - 100) 9.2 (1.4 – 16.8) 45.2 (20.0 – 62.8)

R 89.0 (31 – 100) 69.9 (25 - 100) 9.9 (0.7 – 21.7) 46.9 (32.8 – 66.6)

5 years follow-up

0.526

0.555

0.042

0.186

p-value

54.7 (23.2 – 68.1)

Mental score

Data in Mean (range) KSS = Knee Society Score

32.2 (0.0 – 50.8)

0.97 (0.71 – 1.15)

Function score

SF-12

Ratio single stance

55.0 (32.8 – 68.3)

28.2 (0.0 – 50.0)

1.05 (0.54 – 1.40)

55.1 (33.2 – 63.5)

43.5 (17.3 – 56.6)

0.99 (0.80 – 1.21)

54.7 (38.4 – 63.1)

43.6 (25.0 – 56.6)

1.03 (0.78 – 1.68)

1.00 (0.90 – 1.14) 42.9 (17.1 – 59.7) 55.4 (33.7 – 64.2)

1.01 (0.82 – 1.52) 43.6 (26.6 – 55.5) 54.5 (36.4 – 65.6)

0.816

0.398

0.112

Single stance affected leg 0.405 (0.34 – 0.59) 0.435 (0.30 – 0.67) 0.390 (0.30 – 0.46) 0.421 (0.35 – 0.72) 0.394 (0.30 – 0.47) 0.412 (0.34 – 0.52) 0.523

Temporal gait parameters

8.3 (-5.5 – 26.6)

Max Stance

Goniometry

50.8 (0 – 87)

Knee score

KSS

Baseline

D OES INSERT TYPE AFFECT OUTCOME IN TKA?

PART 1 | C H APTE R 4

Table 5. Number of revisions and manipulations during the follow-up period Â Revision

Fixed Bearing 1* 7 DD ND 1* 0 4 3

Manipulation

Â Revision Manipulation

p-value 1.000 0.780

Mobile Bearing 6** 10 R R/T 2 4 2 8

p-value 0.058 0.358 p-value 0.434 0.051

* Revision <2 weeks after surgery because of acute PJI, patient included in further analysis ** Reasons for revision: - 2x loosening of tibial component - 2x limited ROM - 1x loosening of insert screw - 1x infection

1.0

Fixed Bearing Mobile Bearing

Cumulative Survival

0.8

0.6

0.4

0.2

0.0 0

500

1000

1500

2000

Time to Revision (Days)

Figure 2: Kaplan-Meier curves showing the cumulative survival of patients in the MB-TKA group and FB-TKA group over time. The difference was significant (p=0.047).

D OES INSERT TYPE AFFECT OUTCOME IN TKA?

DISCUSSION We conducted a randomised controlled trial to compare the clinical and functional results of FB-TKA and MB-TKA, and to evaluate the results two different types of insert for each type of bearing in a group of 237 patients. There were no clear differences in KSS scores, gait parameters and QoL between either the bearing or insert groups. However, there were six times more revisions in the MB-TKA group, mostly in R/T patients. Whether MB-TKA actually results in clinically better knee kinematics has been subject of discussion3,5,6. In vivo, posterior condylar translation and tibial axial rotation in flexion have been shown to be similar in patients with MB-TKA and FB-TKA26. For function7-10, radiological outcome8,11 and quality of life7 generally no significant differences between both types of TKA were reported, although one meta-analysis did find lower pain scores in MB-TKA27. Furthermore, there are indications of an interaction with age, as younger patients tended to show better outcomes for the MB-TKA13. Clinical function of the knee was primarily assessed in the current study using the KSS. In an RCT by Jolles et al.8 with a five year follow-up that included a total of 55 patients, no difference in the KSS was shown between MB-TKA and FB-TKA. This was confirmed by other studies28,29. No significant interaction between the bearing groups was found in the current study. The increase in function score between the R and R/T insert groups was significantly different. The effect size of this finding calculated as described by Kirk et al30 was small to medium with an Ď&#x2030;Â˛ of 0.03. Combined with the QoL results, which did not show a difference between the R and R/T insert groups, this finding does not have consequences for the decision between an R or R/T insert. Based on the primary outcome parameters it is therefore not possible to distinguish between MB-TKA and FB-TKA. Differences between FB-TKA and MB-TKA in functional outcome have also been explored using gait analyses. Assuming that MB-TKA is associated with a more natural motion of the knee, it is expected that both temporal and spatial gait parameters are more similar to a non-pathological, symmetrical, walking pattern. Goniometry measurements, temporal gait parameters and QoL measurements did not differ between either bearing or insert groups in this study, which is consistent with findings in earlier studies with small numbers of participants, that did not show significant differences in gait parameters between FB-TKA and MBTKA7,8,12,13. A six times higher number of revisions was found in the MB group and 4 of those patients had an R/T insert. When looking at all other parameters measured in this

PART 1 | C H APTE R 4

study no evident reason for the higher number of revisions and manipulations in the R/T group and MB group could be found. Only two revisions (those revised because of tibial loosening) could possibly be explained as implant related. The other revisions could have been due to patient related factors like obesity or level of activity, but since it only concerns a very small number we have been unable to distil any clear risk factors. One theorised benefit of MB-TKA is less wear which should result in less revisions5 on the long term, but this has been subject of discussion5,31,32. A follow-up period of 5 years is not sufficient to comment on differences of wear leading to a revision procedure. The higher revision rate found in the current study in MB-TKA has also been described by Gupta et al.33, with five years follow-up. Longer follow-up is necessary to provide a complete picture of the revision rates, since revision rates become higher as time progresses after placement2. Limitations There was a large drop-out rate of 38.4% (n=91). Because the drop-out analysis did not show any differences with the analysed group, the likelihood that it biased our results is minimal. Also, there remained enough patients in all groups to ensure sufficient power for the analysis. However, a larger sample size provided by fewer patients lost to follow up could have resulted in a p<0.05 in some statistical comparisons. Due to logistical reasons it was not possible to ensure that all measurements were taken by an assessor who was blinded for the group allocation of the patients. Although this could be a potential source of bias we expect that, because this study was neutrally designed to discover possible differences between FB-TKA and MB-TKA, it did not have a significant influence on the results. It has been shown that most revisions are necessary after 10-15 years34, which indicates that to be able to make a definitive statement on the differences in number of revisions between FB-TKA and MB-TKA longer follow-up would be necessary. Generalizability Our study was performed in a representative population that would be eligible for TKA. The findings in our primary outcome parameters confirm the findings of earlier studies that showed no difference in clinical function between FB-TKA and MB-TKA up to 5 years after surgery. Only one type of total knee prosthesis was studied, and whether insert type has consequences in other types of prosthesis is unclear.

D OES INSERT TYPE AFFECT OUTCOME IN TKA?

CONCLUSION An RCT was performed in 146 patients that received either an FB or MB total knee prosthesis with two types of inserts for each bearing. Knee function, quality of life and temporal gait parameters did not show a clinically significant difference for both type of bearing and type of insert used. Compared to the MB-TKA, the survival of the FB-TKA with respect to revisions for any reason was better and the number of manipulations was lower, especially when an R/T insert was used. However, considering the dropout rate of 38% and the low number of revisions because of mechanical loosening, further long-term analysis is necessary to draw definitive conclusions. The results of the current study do, however, indicate that when using the Genesis II implant system FB-TKA may be preferential over MBTKA. Conflict of interest statement This study was partly funded by Smith & Nephew, London, United Kingdom. They did not play a role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and/or in the decision to submit the article for publication.

PART 1 | C H APTE R 4

REFERENCES 1. Otten R, van Roermund PM, Picavet HS. Trends in the number of knee and hip arthroplasties: considerably more knee and hip prostheses due to osteoarthritis in 2030: Ned Tijdschr Geneeskd 2010; 154: A1534 2. Kurtz S, Mowat F, Ong K, Chan N, Lau E, Halpern M. Prevalence of primary and revision total hip and knee arthroplasty in the United States from 1990 through 2002: J Bone Joint Surg Am 2005; 87: 1487-1497 3. Wasielewski RC, Komistek RD, Zingde SM, Sheridan KC, Mahfouz MR. Lack of axial rotation in mobile-bearing knee designs: Clin Orthop Relat Res 2008; 466: 2662-2668 4. Buechel FF, Pappas MJ. The New Jersey Low-Contact-Stress Knee Replacement System: biomechanical rationale and review of the first 123 cemented cases: Arch Orthop Trauma Surg 1986; 105: 197-204 5. van Duijvenbode DC, Hoozemans MJM, Fieten GM, Burger BJ. Primaire totale knieprothese, ‘mobile bearing’ of een ‘fixed bearing’? - een overzicht van de literatuur: Nederlands Tijdschrift voor Orthopaedie 2013; 20: 36-48 6. Ranawat CS, Komistek RD, Rodriguez JA, Dennis DA, Anderle M. In vivo kinematics for fixed and mobile-bearing posterior stabilized knee prostheses: Clin Orthop Relat Res 2004; 184-190 7. Cheng M, Chen D, Guo Y, Zhu C, Zhang X. Comparison of fixed- and mobile-bearing total knee arthroplasty with a mean five-year follow-up: A meta-analysis: Exp Ther Med 2013; 6: 45-51 8. Ladermann A, Lubbeke A, Stern R, Riand N, Fritschy D. Fixed-bearing versus mobile-bearing total knee arthroplasty: a prospective randomised, clinical and radiological study with mid-term results at 7 years: Knee 2008; 15: 206-210 9. Smith H, Jan M, Mahomed NN, Davey JR, Gandhi R. Meta-analysis and systematic review of clinical outcomes comparing mobile bearing and fixed bearing total knee arthroplasty: J Arthroplasty 2011; 26: 1205-1213 10. Wen Y, Liu D, Huang Y, Li B. A meta-analysis of the fixed-bearing and mobile-bearing prostheses in total knee arthroplasty: Arch Orthop Trauma Surg 2011; 131: 1341-1350 11. Pijls BG, Valstar ER, Kaptein BL, Nelissen RG. Differences in long-term fixation between mobilebearing and fixed-bearing knee prostheses at ten to 12 years’ follow-up: a single-blinded randomised controlled radiostereometric trial: J Bone Joint Surg Br 2012; 94: 1366-1371 12. Tibesku CO, Daniilidis K, Skwara A, Dierkes T, Rosenbaum D, Fuchs-Winkelmann S. Gait analysis and electromyography in fixed- and mobile-bearing total knee replacement: a prospective, comparative study: Knee Surg Sports Traumatol Arthrosc 2011; 19: 2052-2059 13. Jolles BM, Grzesiak A, Eudier A, Dejnabadi H, Voracek C, Pichonnaz C et al. A randomised controlled clinical trial and gait analysis of fixed- and mobile-bearing total knee replacements with a five-year follow-up: J Bone Joint Surg Br 2012; 94: 648-655 14. Aigner C, Windhager R, Pechmann M, Rehak P, Engeleke K. The influence of an anterior-posterior gliding mobile bearing on range of motion after total knee arthroplasty. A prospective, randomized, double-blinded study: J Bone Joint Surg Am 2004; 86-A: 2257-2262 15. Berend KR, Lombardi AV, Jr., Adams JB. Which total knee replacement implant should I pick? Correcting the pathology: the role of knee bearing designs: Bone Joint J 2013; 95-B: 129-132 16. Daniilidis K, Skwara A, Vieth V, Fuchs-Winkelmann S, Heindel W, Stuckmann V et al. Highly conforming polyethylene inlays reduce the in vivo variability of knee joint kinematics after total knee arthroplasty: Knee 2012; 19: 260-265 17. Laskin RS, Maruyama Y, Villaneuva M, Bourne R. Deep-dish congruent tibial component use in total knee arthroplasty: a randomized prospective study: Clin Orthop Relat Res 2000; 36-44 18. Dixon JR, Jr. The International Conference on Harmonization Good Clinical Practice guideline: Qual Assur 1998; 6: 65-74 19. World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA 2013; 310: 2191-2194 20. Bourne RB, Laskin RS, Guerin JS. Ten-year results of the first 100 Genesis II total knee replacement procedures: Orthopedics 2007; 30: 83-85

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21. Laskin RS, Davis J. Total knee replacement using the Genesis II prosthesis: a 5-year follow up study of the first 100 consecutive cases: Knee 2005; 12: 163-167 22. Bhandari M, Pascale W, Sprague S, Pascale V. The Genesis II in primary total knee replacement: a systematic literature review of clinical outcomes: Knee 2012; 19: 8-13 23. Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system: Clin Orthop Relat Res 1989; 13-14 24. Gandek B, Ware JE, Aaronson NK, Apolone G, Bjorner JB, Brazier JE et al. Cross-validation of item selection and scoring for the SF-12 Health Survey in nine countries: results from the IQOLA Project. International Quality of Life Assessment: J Clin Epidemiol 1998; 51: 1171-1178 25. Girden ER. ANOVA: Repeated Measures: 1992; 26. Shi X, Shen B, Yang J, Kang P, Zhou Z, Pei F. In vivo kinematics comparison of fixed- and mobilebearing total knee arthroplasty during deep knee bending motion: Knee Surg Sports Traumatol Arthrosc 2012; 27. Li YL, Wu Q, Ning GZ, Feng SQ, Wu QL, Li Y et al. No difference in clinical outcome between fixed- and mobile-bearing TKA: a meta-analysis: Knee Surg Sports Traumatol Arthrosc 2014; 22: 565-575 28. van d, V, Pijls BG, Nouta KA, Valstar ER, Jacobs WC, Nelissen RG. A systematic review and metaregression of mobile-bearing versus fixed-bearing total knee replacement in 41 studies: Bone Joint J 2013; 95-B: 1209-1216 29. Delport HP. The Advantage of a Total Knee Arthroplasty with Rotating Platform is Only Theoretical: Prospective Analysis of 1,152 Arthroplasties: Open Orthop J 2013; 7: 635-640 30. Kirk RE. Practical Significance: A Concept Whose Time Has Come: Educational and Psychological Measurement 1996; 56: 746-759 31. McEwen HM, Barnett PI, Bell CJ, Farrar R, Auger DD, Stone MH et al. The influence of design, materials and kinematics on the in vitro wear of total knee replacements: J Biomech 2005; 38: 357-365 32. Grupp TM, Kaddick C, Schwiesau J, Maas A, Stulberg SD. Fixed and mobile bearing total knee arthroplasty--influence on wear generation, corresponding wear areas, knee kinematics and particle composition: Clin Biomech (Bristol , Avon ) 2009; 24: 210-217 33. Gupta RR, Bloom KJ, Caravella JW, Shishani YF, Klika AK, Barsoum WK. Role of primary bearing type in revision total knee arthroplasty: J Knee Surg 2014; 27: 59-66 34. Gothesen O, Espehaug B, Havelin L, Petursson G, Lygre S, Ellison P et al. Survival rates and causes of revision in cemented primary total knee replacement: a report from the Norwegian Arthroplasty Register 1994-2009: Bone Joint J 2013; 95-B: 636-642 35. Schulz KF, Altman DG, Moher D. CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials: PLoS Med 2010; 7: e1000251

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CHAPTER 4.1 Letter to Editor

Does insert type affect clinical and functional outcome in total knee arthroplasty? A randomised controlled clinical trial with 5-year follow-up

Journal of Arthroplasty. 2016 Jul;31(7):1614-5. A Mehtani, J Prakash

PART 1 | C H APTE R 4.1

TO THE EDITOR We would like to congratulate the authors of recently published article “Does Insert Type Affect Clinical and Functional Outcome in Total Knee Arthroplasty? A Randomised Controlled Clinical Trial With 5-Year Follow-Up” to share their experience with us and orthopedic community1. The authors have concluded higher revision rates for mobile bearing liners. However we have a few concerns regarding the study design and conclusion of the study. In our clinical experience, we have found mobile bearing inserts to work well particularly in younger patients. Studies have shown mobile bearing to have a favorable effect in younger patients2. However, authors have taken a wide age range from 50 to 75 years. We would like to know if there was any difference when mobile bearing was used in younger patients (<70 years) compared with older patients. Regarding the study design, we believe that there are lots of confounding factors. Study is single blinded and has not accounted for observer bias. A high dropout rate has been mentioned by authors as limitations of their study. Eight different surgeons with their preferred technique did the surgery which is bound to introduce a high variation. A stratified analysis of results of each surgeon would have been better. Authors have mentioned only preoperative clinical and functional scores; however, no mention of preoperative deformity in each group is mentioned. Were all groups equally matched for preoperative varus deformity and number of valgus knees? Authors have excluded varus of >25 and valgus of >10 degree. Why were larger deformities not included in the study is not mentioned? Also was power analysis done before this study to find out optimum number of cases is not mentioned. Revision in total knee arthroplasty is multifactorial, and a lot of these factors are not discussed by author. There is no mention, if all 4 groups were evenly matched in terms of postoperative lower limb alignment or not. No mention about radiological results of component positioning in each group is provided which in itself may have an effect on revision. It is surprising that only “type of liner” would result in 6-fold increase in shortterm revision. This is not in consensuses to either literature or our own experience. Literature has shown no siginificant difference in both types of liner3-5. Further on analyzing the data, we observed that mobile bearing inserts with both rotational and translational mobility had a higher surgical time than other cases. One of the cases has been mentioned to take 180 minutes. What was the cause of higher surgical time in these inserts is not mentioned.

104

LETTER TO THE ED ITOR

Higher surgical time may in itself cause higher blood loss, higher chances of infection, lower functional scores, and probably high revision. Were these factors considered while analyzing the results? The liner would result in revision through a process of â&#x20AC;&#x153;wearâ&#x20AC;? causing osteolysis of bone radiologically evident as progressive radiolucent lines. However, authors have not mentioned about radiolucent lines in this study. We would request authors to kindly tell if there were any cases with progressive radiolucent lines in any group and if that was statistically significant. We believe that authorsâ&#x20AC;&#x2122; conclusion that fixed bearing has 6 times higher survivability is an extrapolation of results or merely an incidental finding. Our clinical experience and even most literature show no significant differences in 2 types of insert3-5. A better matched study in terms of preoperative deformity and postoperative alignment and component positioning among groups with less variations in surgical technique and time may be required to show these differences more conclusively. Till then, in view of current literature evidence, it is difficult to believe that only type of liners are responsible for such a high revision rate.

105

PART 1 | C H APTE R 4.1

REFERENCES 1.

Fransen BL, Hoozemans MJM, Keijser LCM, et al. Does insert type affect clinical and functional outcome in total knee arthroplasty? A randomised controlled clinical trial with 5-year follow-up. J Arthroplasty 2015;30:1931 2. Jolles BM, Grzesiak A, Eudier A, et al. A randomised controlled clinical trial and gait analysis of fixed- and mobile-bearing total knee replacements with a five year follow-up. J Bone Joint Surg (br) 2012;94:648 3. Ladermann A, Lubbeke A, Stern R, et al. Fixed-bearing versus mobile-bearing total knee arthroplasty: a prospective randomised, clinical and radiological study with mid-term results at 7 years. Knee 2008;15:206 4. Smith H, Jan M, Mahomed NN, et al. Meta-analysis and systematic review of clinical outcomes comparing mobile bearing and fixed bearing total knee arthroplasty. J Arthroplasty 2011;26:1205 5. Wen Y, Liu D, Huang Y, et al. A meta-analysis of the fixed-bearing and mobilebearing prostheses in total knee arthroplasty. Arch Orthop Trauma Surg 2011;131:1341

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LETTER TO THE ED ITOR

107

CHAPTER 4.2 In Reply

Does insert type affect clinical and functional outcome in total knee arthroplasty?

Journal of Arthroplasty. 2016 Jul;31(7):1615-6. BL Fransen, MJM Hoozemans, LCM Keijser, ME van Lent, CCPM Verheyen, BJ Burger

PART 1 | C H APTE R 4.2

TO THE EDITOR We wish to thank the authors of this letter for their interest in our study. We concluded that there was no significant clinical difference between patients that received either a fixed bearing total knee arthroplasty (FB-TKA) or a mobile bearing TKA (MB-TKA) with respect to knee function, quality of life and temporal gait parameters1. This is in accordance with what is generally reported in the literature. We are in the final process of constructing an extensive overview of the literature with over 125 studies (including meta-analyses, systematic reviews, RCTâ&#x20AC;&#x2122;s and comparative studies) that seems to confirm that there is no clear difference in insert wear, risk of loosening, survivorship or clinical outcome between FB-TKA and MB-TKA. The first issue that the authors of the letter raise is the role of age. The randomized design of our study aimed for the groups to be comparable in age at the start of the study, and also, the dropout during the study was not selective (ie, not associated with age). Therefore the randomized clinical trial design is sufficient to balance age between groups. We acknowledge that younger adults might potentially benefit more from a MB-TKA because they might be more active. This question though was not part of our study and requires stratified analyses and thus a strong reduction in statistical power. Moreover, not only age itself, but also the associated higher comorbidities with higher age can influence outcome of TKA2. Therefore, stratifying for age would only partly solve the issue raised by the authors. The second issue concerns the study design. The study design was a multicenter randomized clinical trial with participants blinded for allocation but not all followup measurements were performed by a blinded accessor. This indeed is a flaw in our study as we stated in the article. Knee Society Score and quality of life forms were filled in by the blinded participants and not in the presence of the actual researcher but during regular checkups at the outpatient orthopedic clinics. Therefore, we do not expect these results to be biased because of observer bias. We disagree with the authors of the letter that a multicenter study with multiple surgeons negatively affects the validity of the results. Although a single-center study with only 1 surgeon would theoretically increase the internal validity of a clinical experiment, it strongly reduces the external validity. The potential increase in variation in outcome because of the variation in surgical techniques is comparable to the variation that is present in daily clinical practice, which thus greatly increases the generalizability of the results of the study. Moreover, we intended to keep the internal validity of the study as high as possible by explicitly

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letting all surgeons perform all 4 types of arthroplasty. The randomization procedure causes the pre-operative knee deformities present in the study population (and all other potential confounding factors for that matter) to be equally divided over study groups and not bias the results. Large deformities were chosen as exclusion criteria because in these cases surgical difficulties in balancing the ligaments might be expected. These difficulties can lead to an unstable knee and are a prerequisite for using more constrained implants. One interesting difference between the bearing types observed in our study was that one revision was observed in the FB-TKA group and 6 revisions in the MBTKA group (with n=117 and 105 at 1-year follow-up, respectively), all observed within 1 year after surgery. The number of revisions was actually not significantly different (p=0.058) but the survival curves were (p=0.047). We stated in both discussion and conclusion our reservations with respect to whether this finding is actually caused by the difference in bearing type, as only 2 of the 6 revisions in the MB-TKA group were because of mechanical loosening. Considering the reasons for revision as already described in the article, we feel that additional information â&#x20AC;&#x201C; for instance lower limb alignment, component positioning or operation time (which was actually on average not statistically different between the groups) â&#x20AC;&#x201C; will not (and can not statistically) contribute to a better explanation of the results with such low numbers of revision. In agreement with the authors of the letter to the editor, we concluded in the paper that further analyses of long-term (10-15 years) follow-ups are necessary to draw definitive conclusions.

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REFERENCES 1. Fransen B, Hoozemans MJM, Keijser LCM, van Lent MET, Verheyen CCPM, Burger BJ. Does Insert Type Affect Clinical and Functional Outcome in Total Knee Arthroplasty? A Randomised Controlled Clinical Trial With 5-Year Follow-Up. J Arthroplasty 2015;30:1931–7 2. Peter WF, Dekker J, Tilbury C, Tordoir RL, Verdegaal SHM, Onstenk R, et al. The association between comorbidities and pain, physical function and quality of life following hip and knee arthroplasty. Rheumatol Int 2015;35:1233–41

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PART 2 Improving functional outcome measures

CHAPTER 5 Cross-cultural adaptation and validation of the Dutch version of the High Activity Arthroplasty Score

Nederlands Tijdschrijft voor Orthopedie. 2018;25(3):68-74. BL Fransen, HJ Kan, J Posthuma de Boer, BJ Burger, MJM Hoozemans

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ABSTRACT Introduction The High Activity Arthroplasty Score (HAAS) has been designed to differentiate in functional ability between normal and more active patients after total knee arthroplasty (TKA) and total hip arthroplasty (THA). No such questionnaire is currently available in the Dutch language. The objective of this study was to evaluate the Dutch version of the HAAS in THA and TKA patients. Patients & Methods The forward and backward translated Dutch version of the HAAS combined with the national Dutch patient reported outcome measures (PROMS) were sent to two hundred patients of all ages who underwent TKA or THA. The internal consistency, construct validity and floor/ceiling effects of the HAAS were evaluated. Results 108 patients (51 THA and 57 TKA) participated in this study. A good internal consistency with a Cronbachâ&#x20AC;&#x2122;s alpha of 0.78, 0.81 and 0.84 was found in all patients, the THA and the TKA group respectively. Significant positive correlations were observed between the HAAS and VAS QoL, EQ-5D, all KOOS sub-scores except the symptoms score, and all HOOS sub-scores except the QoL score. A negative correlation was found with the VAS pain. No floor or ceiling effect was seen in the HAAS. Discussion The Dutch version of the HAAS can be used to evaluate the functional ability in more active patients of all ages who underwent THA or TKA with an acceptable internal consistency and construct validity, and no ceiling or floor effects.

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INTRODUCTION The evaluation of outcome of total hip arthroplasty (THA) and total knee arthroplasty (TKA) is often performed by (self-administered) questionnaires. The assessment of these Patient Related Outcome Measures (PROMs) has become standard practice for evaluating pain, function, QoL and patient satisfaction after THA and TKA1. Since both THA and TKA have proven to be very effective treatments with generally very good results,2,3 the most commonly used questionnaires for evaluating THA and TKA provide results in a narrow spectrum of high scores. This results in a ceiling effect, which can interfere with the adequate analysis of research findings.4 Current trends show that more and younger patients are undergoing THA and TKA. These younger patients generally attach more value to other aspects of functional outcome, e.g. having an adequate function to be able to return to work or participate in sports activities.5,6 In addition, older patients who undergo joint replacement remain active on a higher functional level up to a higher age.7 Ceiling effects of current, decades old, questionnaires provide unsatisfactory means to differentiate between function on a high, or an even higher level of functional outcome. To address this issue, Talbot et al. presented a new questionnaire that is able to assess variation in functional ability in highly functioning TKA or THA patients, the High Activity Arthroplasty Score (HAAS).8 The questionnaire was designed to provide a tool to differentiate between functional outcome at a level of daily activities (e.g. walking, stair climbing) and a higher level of functional outcome (e.g. sports). The HAAS has been validated in English and French8,9 and consists of four domains of function: walking, running, stair climbing and activity levels. Since the introduction of the HAAS in 2010, several publications showed that this self-administered questionnaire consistently has good validity and reliability.8â&#x20AC;&#x201C;11 There is no comparable and validated questionnaire available in Dutch that evaluates higher-level functional outcome after TKA and THA. Therefore, the goal of the current study was to translate the HAAS into Dutch and to determine its internal consistency, construct validity, and ceiling and floor effects in patients who underwent primary unilateral THA or TKA. We hypothesized that the HAAS would have good internal consistency, a good correlation with other questionnaires focusing on functional outcome, and no ceiling or floor effect.

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PATIENTS & METHODS Translation procedure The protocol for translating the English version of the HAAS into the Dutch language followed the Guidelines for the Process of Cross-Cultural Adaptation of Self-Report Measures by Beaton et al.12 First, two Dutch orthopaedic residents who were fluent in English and one Dutch professional English translator, who was not working in the medical field, independently translated the HAAS into Dutch. Afterwards a consensus meeting was held in which the three versions were combined into one. Then, two persons whose mother tongue was English, but were also fluent in Dutch, translated this Dutch version back into English. They were not medical professionals and were blinded for the original English version. Using these backward translations, final adjustments to the Dutch version were made in another consensus meeting. Study design and study population The validation study was performed in a large non-university teaching hospital in The Netherlands. One hundred patients who underwent primary THA and one hundred patients who underwent primary TKA for osteoarthritis between the 1st of July 2015 and the 31st of December 2015 were sent a questionnaire 6 to 12 months after surgery. They were asked to fill in the questionnaire (including an informed consent form) and return it by mail. Patients who reported comorbidities that could influence physical functioning in daily activities (i.e. lower back pain, Parkinsonâ&#x20AC;&#x2122;s disease, other joints with OA etc.) were excluded. In the present study we decided to include all ages so the study population would accurately represent the orthopaedic population that undergoes TKA or THA. This is contrary to the original validation by Talbot et al. who only included patients under 66 years, but consistent with Jenny et al. who showed the HAAS can be used in elderly patients as well10. Questionnaires The Dutch translation of the HAAS (Table 1) was sent as a part of a questionnaire that also included a visual analogue scale (VAS) for pain, the EQ-5D13 for quality of life (QoL) (which includes VAS for QoL) and either the Hip disability and Osteoarthritis Score (HOOS)14 or the Knee disability and Osteoarthritis Score (KOOS),15 depending on whether they underwent THA or TKA. All questionnaires except the HAAS were validated in Dutch and part of our regular PROMs. The four questions of the HAAS result in a score ranging from 0 to 18, with 18 indicating the highest function. The VAS for pain scores (at the time of response)

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Table 1. The Dutch translation of the HAAS Nederlandse versie van de HAAS Geef voor elk van de vier categorieĂŤn aan wat uw hoogste niveau van functioneren is. 1 Lopen (max 5 punten) 5 over een ongelijkmatige ondergrond > 1 uur 4 onbeperkt over vlakke ondergrond, moeizaam over ongelijkmatige ondergrond 3 onbeperkt over vlakke ondergrond, onmogelijk over ongelijkmatige ondergrond 2 minstens 30 minuten op vlakke ondergrond 1 korte afstanden (tot 20 meter) zonder hulp 0 gebruik loophulpmiddelen bij korte afstanden of een nog lager niveau van functioneren 2 Hardlopen (max 4 punten) 4 meer dan 5 km 3 rustig joggen tot 5 km 2 gemakkelijk hardlopen om de straat over te steken 1 een paar passen hardlopen om een eventuele botsing in het verkeer te voorkomen 0 kan niet hardlopen

3 Trap oplopen (max 3 punten) 3 met 2 treden tegelijk trap oplopen 2 trap oplopen zonder leuning te gebruiken 1 trap oplopen met leuning of wandelstok 0 kan geen trap oplopen 4 Activiteitsniveau (max 6 punten) 6 prestatiegericht sporten, b.v. enkelspel tennis, > 10km hardlopen, > 80 km fietsen 5 recreatief sporten, b.v. dubbelspel tennis, skiĂŤn, < 10 km joggen, intensieve aerobics 4 inspannende recreatieve activiteiten, b.v. bergwandelen, lichte aerobics, flink tuinieren of ander handmatig zwaar werk 3 matig inspannende recreatieve activiteiten, b.v. golfen, tuinieren of ander licht werk 2 licht inspannende recreatieve activiteiten, b.v. een korte wandeling, jeu de boules 1 alleen noodzakelijke buitenactiviteiten, b.v. een klein stukje wandelen om een boodschap te doen 0 zonder hulp aan huis gebonden (max 18 punten)

ranged from zero, indicating no pain, to 100, indicating the worst pain imaginable. The EQ-5D consists of five questions concerning QoL, each with three possible answers, and a VAS for QoL. A combined score of the five questions is calculated ranging from zero (worst) to one (best), with a separate score for the VAS for QoL.16 The KOOS and HOOS each contain five subscores (symptoms, pain, activities of daily living (ADL), sports and recreation, QoL), with scores ranging from zero (worst) to 100 (best).14,15

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Sample size For cross-cultural adaptations, a minimum of 30-40 patients is considered to be sufficient to make adequate calculations.12 Our study met the quality criteria proposed by Terwee and associates17 for measurement properties of health status questionnaires, which require the results from at least 50 patients for the analysis of ceiling or floor effects, reliability and validity. Statistical analysis The results were analyzed for all patients together, as well as for THA and TKA patients separately. To assess the reliability of the translated Dutch version of the HAAS, the internal consistency was tested by determining Cronbach’s α, indicating the level of interrelatedness of the items in the Dutch HAAS questionnaire.18 An α of 0.7 – 0.95 was deemed acceptable.19 Since a gold standard is not available, the construct validity of the HAAS was evaluated by determining its association with the scores on the VAS pain, EQ-5D, VAS QoL of the EQ-5D and KOOS or HOOS using Spearman’s rank correlation coefficient (r). A correlation of 0.10 was considered a weak association, a correlation of 0.30 was considered a moderate association and a correlation of 0.50 or higher was considered a strong association.20,21 To evaluate a possible ceiling effect, the criteria by McHorney and Tarlov22 were used, in which a ceiling or floor effect is determined as 15% or more of patients achieving the maximal or minimal score on a questionnaire. All statistical analyses were performed using IBM SPSS Statistics version 20 (IBM Corporation, Armonk, NY, USA).

RESULTS Patient characteristics In total, 200 patients (100 THA and 100 TKA) received the questionnaire. Of these, 144 (72%) (67 THA and 77 TKA) were willing to participate and completed the questionnaire. After excluding the patients that reported comorbidities that potentially influence their physical functional ability, 51 THA (76%) and 57 TKA (74%) patients were included for analysis. The mean age at time of surgery for all patients was 70 (range 42-86) years. Thirty-one patients (32.4%) were aged 65 or younger. All patient characteristics can be found in Table 2. Seven patients (6.5%) did not answer one or more of the questions of the HAAS. Their HAAS scores were excluded from analysis.

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Table 2. Patient characteristics for all patients, the total hip arthroplasty (THA) and total knee arthroplasty (TKA) group

Age at time of surgery (years) Gender Female Male BMI Side Left Right

All n=108 70 (42 - 86) 60 (55.6%) 48 (44.4%) 27.3 (19.5 – 46.6) 48 (44.4%) 60 (55.6%)

THA n=51 69 (42 - 86) 33 (64.7%) 18 (35.3%) 26.5 (19.5 – 34.9) 20 (39.2%) 31 (60.8%)

TKA n=57 72 (51 - 85) 27 (47.4%) 30 (52.6%) 28.2 (21.1 - 46.6) 28 (49.1%) 29 (50.9%)

Data in Mean (range) or Number (%). BMI = Body Mass Index

Internal consistency and construct validity Cronbach’s α for the Dutch translation of the HAAS demonstrated a good internal consistency of 0.780 for all patients and an internal consistency of 0.810 and 0.838 for the THA and TKA groups, respectively. The Spearman’s rank correlation was used to explore construct validity. We observed a significant negative association between the HAAS scores and VAS for pain in all three groups (Table 3). The observed associations were moderate. Significant positive associations were observed between HAAS and VAS QoL, EQ-5D, all KOOS sub-scores except the symptoms score, and all HOOS sub-scores except the QoL score. All associations were weak or moderate, except for the association between the HAAS and the KOOS ADL and Sports & Recreation sub-scores and the association between the HAAS and the HOOS Symptoms and Sports and Recreation sub-scores, which showed a strong association (Table 3). Ceiling or floor effect No ceiling or floor effect was found for the HAAS in any of the groups. The distribution of the HAAS scores is displayed in Figure 1. No floor or ceiling effect was observed for the VAS QoL in all groups, nor for the KOOS symptoms, ADL and Sport & Recreation sub-scores (in the TKA group). Analyses of the TKA, THA and total groups showed a floor effect for the VAS pain. A ceiling effect was found for all other scores. Table 4 summarizes the floor and ceiling effects for the different outcome measures in THA and TKA.

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Figure 1. HAAS scores distribution This figure shows the distribution of HAAS scores among all patients and the study population of TKA and THA patients.

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Table 3. Cronbachs alpha and Spearman’s rank correlation coefficient (r)

Internal consistency HAAS (Cronbach’s alpha) Construct validity (Spearman’s rho) HAAS & VAS pain

HAAS & VAS QoL HAAS & EQ-5D HAAS & KOOS Symptoms score

Pain score ADL score Sport & Recreation score QoL score

HAAS & HOOS Symptoms score Pain score ADL score

Sport & Recreation score QoL score

All n=108 0.780

THA n=51 0.810

TKA

-.378 (p<.001) .286 (p=.004) .466 (p<.001)

-.303 (p=.041) .417 (p=.004) .470 (p=.001) .534 (p<.001) .313 (p=.032) .461 (p=.001) .602 (p<.001) .242 (p=.097)

-.357 (p=.009) .290 (p=.035) .447 (p=.001) .182 (p=.201) .379 (p=.006) .559 (p<.001) .674 (p<.001) .392 (p=.004)

n=57 0.838

A ρ of 0.10 was considered a weak association, 0.30 was considered moderate and a ρ of 0.50 or higher was considered a strong association 20,21. HAAS=High Activity Arthroplasty Score; THA=total hip arthroplasty; TKA=total knee arthroplasty; VAS=visual analogue scale; QoL=quality of life; KOOS=Knee disability and Osteoarthritis Score; ADL=activities of daily living; HOOS=Hip disability and Osteoarthritis Score

DISCUSSION In this work, a translation and validation of the HAAS into Dutch was performed. We found a Cronbach’s α of 0.780 for THA and TKA combined indicating a very good internal consistency. Moreover, when analyzing THA and TKA separately, the Cronbach’s α scores remained high with 0.810 and 0.838 for the THA and TKA groups respectively. This is in line with earlier studies; in their original paper, Talbot et al. found a Cronbach’s α of 0.86 for THA and TKA combined.8 Another study by Diesinger et al. described an α of 0.58 in the French version of the HAAS for TKA patients.9

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Table 4. Ceiling and floor effects

No Floor or Ceiling effect

All n=108 HAAS VAS QoL

THA n=51 HAAS VAS QoL

Ceiling effect

Floor effect

EQ5D (49.0%)

EQ5D (56.9%) HOOS Symptoms score (25.5%) HOOS Pain score (37.3%) HOOS ADL score (27,5%) HOOS Sport score (19.6%) HOOS QoL score (29.4%) VAS pain (49.1%) VAS pain (58,8%)

TKA n=57 HAAS VAS QoL KOOS Symptoms score KOOS ADL score KOOS Sport score EQ5D (36.8%) KOOS Pain score (22.8%) KOOS QoL score (17.5%)

VAS pain (38,6%)

A ceiling or floor effect is determined as 15% or more of patients achieving the maximal or minimal score on a questionnaire. Percentage of patients scoring the highest or lowest score for ceiling and floor effects, respectively. HAAS=High Activity Arthroplasty Score; THA=total hip arthroplasty; TKA=total knee arthroplasty; VAS=visual analogue scale; QoL=quality of life; KOOS=Knee disability and Osteoarthritis Score; ADL=activities of daily living; HOOS=Hip disability and Osteoarthritis Score

To evaluate the construct validity of the Dutch HAAS, the associations between the Dutch version of the HAAS and the questionnaires used in the national PROMs (i.e., HOOS, KOOS, EQ-5D, and VAS for pain), were studied. A significant positive correlation was seen between HAAS and VAS QoL, EQ-5D, all KOOS sub-scores except the symptoms score, and all HOOS sub-scores except the QoL score. This showed that patients that have high functional scores in the PROMs also have high HAAS scores. A negative correlation was seen between the HAAS and VAS for pain. Thus, with lower pain scores, higher HAAS scores are observed, indicating that the patient is functioning well. In line with our hypotheses, the HAAS showed better associations with other questionnaires focusing on functional outcome, such as the sports and recreation subscore of the KOOS and HOOS, compared to the PROMs that measure clinical outcome. The Dutch version of the HAAS showed weak, moderate and strong associations with the PROMs commonly used in the Netherlands. In both the English and French validation of the HAAS,8,9 the American Knee Society Score (AKSS) and Oxford Knee Score (OKS) were used. We used the KOOS and the HOOS for exploring the construct validity of the Dutch HAAS since these are included in our national PROMs. However, since the KOOS and HOOS

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also contain both clinical and functional questions it is to be expected that associations between the Dutch HAAS, AKSS and OKS would be similar to those found between the Dutch HAAS, HOOS and KOOS in the current study. No floor or ceiling effect was observed in the Dutch HAAS, which is consistent with reports of the HAAS in other languages, which did not show these effects either. Jenny et al.10 confirmed the absence of ceiling and floor effects in the English version of the HAAS in TKA patients of all ages, one year after surgery in 2014, as opposed to both the AKSS and the OKS. Thus, the results of the HAAS in studies so far indicate that it is better in analyzing differences in both low and higher levels of functional outcome for younger and older total joint arthroplasty patients, compared to the HOOS/KOOS, AKSS and OKS. Originally, the HAAS has been developed and validated in patients below 66 years old, since they are more likely to have a higher functional level. This was also confirmed by a pilot study the authors had performed8. However, trends show that older patients undergoing lower limb total joint arthroplasty are increasingly active, remain more active up to a higher age7 and some even participate in high impact sports (i.e. alpine skiing, tennis).23 A later article by Jenny et al. demonstrated that the HAAS could be used in TKA patients of all ages with good results. Therefore, patients with higher ages were also included in this study. We find that this increased the external validity of this study of the cross-cultural adaptation and validation of the HAAS because we show that the HAAS is applicable to the general orthopedic population, and not only to a selected group of patients younger than 66 years. By excluding patients that reported comorbidities that potentially influenced their functional levels, the homogeneity of the groups concerning functional activity was increased. However, since comorbidity has been shown to influence outcome scores,24 the influence of comorbidity on the Dutch HAAS scores should be subject of further study. Using questionnaires to measure PROMs has become common practice to evaluate and compare outcome of joint arthroplasty. However, several regularly used questionnaires, such as the HOOS/KOOS and EQ-5D, have been developed several decades ago and have shown limitations such as floor and ceiling effects.1 This notion, combined with the knowledge that arthroplasty patient populations and characteristics have changed over the last decades,7 may give rise to the need for new and improved easy-to-use self-administered questionnaires. The HAAS seems to be a promising alternative. However, before the HAAS could be included in day-to-day practice, further research is necessary. For example, treatment effect measurements could be tested to show whether it may be possible to use the HAAS scores to detect changes in patients before and after an intervention.

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A limitation of this study is the lack of a reliability study with a proper test-retest design, as patients were only asked to fill in the questionnaire once. To our knowledge this has not been done in any of the HAAS validations. Finally, it must be noted that in 6.5% of patients one or more questions of the HAAS were left blank. No clear pattern or cause for these omissions could be deducted from the data collected in this study, and the response patterns could therefore be a subject of further study. Follow-up ranged between 6 and 12 months after surgery, which could also have introduced bias. Patients that are 1 year after surgery might have a better function compared to 6 months after surgery. This was not reflected in our data as a difference in outcome scores. Another factor of influence could be the gender distribution. In general, more women than men undergo arthroplasty surgery, but in the TKA group of the present study 52.6% were men. Since men are known to have a better function before and after TKA25,26, this could have influenced our results by showing higher overall scores for the entire TKA group than might be expected in a normal orthopaedic population with average gender distribution.

CONCLUSION The cross-cultural adaptation of the HAAS into Dutch as presented in this study can be used to evaluate function in patients who underwent THA or TKA with an acceptable internal consistency, good construct validity, and no ceiling or floor effects. Acknowledgements We acknowledge the help of all the translators, and thank Dr. M. van Smeden for his help with the statistical analysis.

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REFERENCES 1. Harris K, Dawson J, Gibbons E, Lim C, Beard D, Fitzpatrick R, et al. Systematic review of measurement properties of patient-reported outcome measures used in patients undergoing hip and knee arthroplasty. Patient Relat Outcome Meas 2016;7:101–8 2. Shan L, Shan B, Suzuki A, Nouh F, Saxena A. Intermediate and long-term quality of life after total knee replacement: a systematic review and meta-analysis. J Bone Joint Surg Am 2015;97:156–68 3. Shan L, Shan B, Graham D, Saxena A. Total hip replacement: a systematic review and metaanalysis on mid-term quality of life. Osteoarthritis Cartilage 2014;22:389–406 4. Thompson SM, Salmon LJ, Webb JM, Pinczewski LA, Roe JP. Construct Validity and Test Re-Test Reliability of the Forgotten Joint Score. J Arthroplasty 2015;30:1902–5 5. Kievit AJ, van Geenen RCI, Kuijer PPFM, Pahlplatz TMJ, Blankevoort L, Schafroth MU. Total knee arthroplasty and the unforeseen impact on return to work: a cross-sectional multicenter survey. J Arthroplasty 2014;29:1163–8 6. Witjes S, van Geenen R, Koenraadt K, van der Hart C, Blankevoort L, Kerkhoffs G, et al. Expectations of younger patients concerning activities after knee arthroplasty: are we asking the right questions? Qual Life Res 2017;26(2):403-417 7. Maradit Kremers H, Larson D, Crowson C, Kremers W, Washington R, Steiner C, et al. Prevalence of Total Hip and Knee Replacement in the United States. J Bone Jt Surg 2015;97:1386–97 8. Talbot S, Hooper G, Stokes A, Zordan R. Use of a new high-activity arthroplasty score to assess function of young patients with total hip or knee arthroplasty. J Arthroplasty 2010;25:268–73 9. Diesinger Y, Jenny J-Y. Validation of the French version of two on high-activity knee questionnaires. Orthop Traumatol Surg Res 2014;100:535–8 10. Jenny J-Y, Louis P, Diesinger Y. High Activity Arthroplasty Score has a lower ceiling effect than standard scores after knee arthroplasty. J Arthroplasty 2014;29:719–21 11. Gagnier J, Mullins M, Huang H, Marinac-Dabic D, Ghambaryan A, Eloff B, et al. A Systematic Review of Measurement Properties of Patient-Reported Outcome Measures Used in Patients Undergoing Total Knee Arthroplasty. J Arthroplasty 2017;32(5):1688-1697 12. Beaton DE, Bombardier C, Guillemin F, Ferraz MB. Guidelines for the process of cross-cultural adaptation of self-report measures. Spine (Phila Pa 1976) 2000;25:3186–91 13. Lamers LM, McDonnell J, Stalmeier PFM, Krabbe PFM, Busschbach JJ V. The Dutch tariff: results and arguments for an effective design for national EQ-5D valuation studies. Health Econ 2006;15:1121–32 14. de Groot I, Reijman M, Terwee C, Bierma-Zeinstra S, Favejee M, Roos E, et al. Validation of the Dutch version of the Hip disability and Osteoarthritis Outcome Score. Osteoarthritis Cartilage 2007;15:104–9 15. de Groot IB, Favejee MM, Reijman M, Verhaar JAN, Terwee CB. The Dutch version of the Knee Injury and Osteoarthritis Outcome Score: a validation study. Health Qual Life Outcomes 2008;6:16 16. Brooks R. EuroQol: the current state of play. Health Policy 1996;37:53–72 17. Terwee C, Bot S, de Boer M, van der Windt D, Knol D, Dekker J, et al. Quality criteria were proposed for measurement properties of health status questionnaires. J Clin Epidemiol 2007;60:34–42 18. Mokkink L, Terwee C, Patrick D, Alonso J, Stratford P, Knol D, et al. The COSMIN checklist for assessing the methodological quality of studies on measurement properties of health status measurement instruments: an international Delphi study. Qual Life Res 2010;19:539–49 19. Tavakol M, Dennick R. Making sense of Cronbach’s alpha. Int J Med Educ. 2011; 2: 53–5. 20. Cohen J. Statistical power analysis for the behavioural sciences. 2nd ediditon. New York: Academic Press; 1988 21. Cohen. Things I have learned (so far). Am Psychol 1990;45:1304–12 22. McHorney CA, Tarlov AR. Individual-patient monitoring in clinical practice: are available health status surveys adequate? Qual Life Res 1995;4:293–307 23. Mayr HO, Reinhold M, Bernstein A, Suedkamp NP, Stoehr A. Sports Activity Following Total Knee Arthroplasty in Patients Older than 60 Years. J Arthroplasty 2015;30:46–9

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24. Peter W, Dekker J, Tilbury C, Tordoir R, Verdegaal S, Onstenk R, et al. The association between comorbidities and pain, physical function and quality of life following hip and knee arthroplasty. Rheumatol Int 2015;35:1233–41 25. Cherian JJ, O’Connor MI, Robinson K, Jauregui JJ, Adleberg J, Mont MA. A Prospective, Longitudinal Study of Outcomes Following Total Knee Arthroplasty Stratified by Gender. J Arthroplasty 2015;30: 1372–7 26. Parsley BS, Bertolusso R, Harrington M, Brekke A, Noble PC. Influence of Gender on Age of Treatment with TKA and Functional Outcome. Clin Orthop Relat Res 2010;468:1759–64

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CHAPTER 6 Gait quality assessed by trunk accelerometry after total knee arthroplasty and its association with patient related outcome measures

Accepted for publication in Clinical Biomechanics BL Fransen, N Mathijssen, K Slot, N De Esch, H Verburg, OPP Temmerman, MJM Hoozemans, JH van DieĂŤn

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ABSTRACT Background With an increasingly younger population and more active patients, assessment of functional outcome is more important than ever in patients undergoing total knee arthroplasty. Accelerometers have been used successfully to objectively evaluate gait quality in other fields. The aim of this study was to assess gait quality with accelerometers before and after surgery, and to assess added value of resulting parameters to patient reported outcome measures scores. Methods Sixty-five patients (mean age 65 years (range 41-75)) who underwent primary total knee arthroplasty were evaluated using a tri-axial trunk accelerometer preoperatively and one year after surgery. Gait quality parameters derived from the accelerometry data were evaluated in three dimensions at both time points. Factor analysis was performed on all outcome variables and changes from before to one year after surgery in the most representative variable for each factor were studied. Findings Factor analysis identified three separate gait quality factors, with questionnaire and gait quality parameters loading on different factors. Both gait quality factor scores and questionnaire factor scores improved significantly one year after surgery. As expected based on the factor analysis, only weak to moderate associations were found between patient reported outcome measures and gait quality before surgery, after surgery and in change scores. Interpretation The independence of patient reported outcome measures and gait quality parameters measured with trunk accelerometry indicates that gait quality parameters provide additional information on functional outcome after total knee arthroplasty. Providing caretakers with objectively measurable targets using accelerometry could help improve outcome of these patients.

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INTRODUCTION Osteoarthritis (OA) of the knee is a degenerative joint disease, disabling approximately 6% of the adults of 30 years and older1. Total knee arthroplasty (TKA) is successfully used to treat moderate to severe OA. During the last decades, the prevalence of OA and the number of TKAs has increased strongly and is expected to increase further, because of demographic trends in obesity and life expectancy and because TKAs are increasingly performed in younger patients2,3. To measure clinical outcome and monitor the results of TKA, mostly patient reported outcome measures (PROMs) are used. These questionnaires allow patients to report their quality of life, level of functioning and other outcome variables, and are used because they have a high internal consistency, are relatively easy to complete, and are cost-effective4. There are indications that PROMs may not fully capture the details of limitations in patient functional performance after TKA5. This might be partially due to the fact that PROMs outcome is influenced by, amongst others: pain, patient expectations, function of the non-operated limb, and functional status before the surgery4,6. Because of the increased number of relatively young patients undergoing TKA surgery and patients remaining active to an older age, recovery of functional abilities has become increasingly important in a patient who has undergone a TKA. It could therefore be argued that more detailed analysis of functional outcome, especially gait, could be of added value and could give a better understanding of changes in functional performance after TKA6,7. More detailed gait analysis of TKA patients using accelerometers, aimed at spatiotemporal parameters in short bouts of gait, has already provided indications that objective functional measurements can be an addition to clinical outcome measured with subjective PROMs8. Using accelerometers, quality of gait measurements can be assessed in a clinical or domestic setting, in larger cohorts of patients, and in a relatively inexpensive way9. These earlier studies were done in smaller groups, and did not determine the added value of gait quality to the assessment of PROMs. Also, no trunk accelerometry has been used, which has shown to be a valid and reliable method to objectively assess gait quality9. With trunk accelerometry, an accelerometer is placed at the lower lumbar spine, which allows the device to collect data on gait stability, symmetry, and smoothness, as well as spatiotemporal gait features10. Therefore, analysis of gait quality using trunk accelerometry in TKA patients could provide a more detailed analysis of symmetry, stability and smoothness of gait in these patients, in addition to clinical outcome assessed using PROMs.

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The goal of the present study was to use trunk accelerometers for instrumented analysis of gait quality parameters (i.e. stability, symmetry, and smoothness) of patients before and 1 year after unilateral primary TKA. The associations between these parameters and several commonly used PROMs were studied, to provide insight into whether gait quality parameters contain independent information on functional outcome after TKA that could be an addition to PROMs.

METHODS Study design and study population A prospective multicenter, observational study was performed in two large nonuniversity teaching hospitals in The Netherlands between 1 July 2014 and 1 July 2017. This study was performed in accordance with the Declaration of Helsinki11. Institutional review board approval was received from the Medical Ethical Committee Zuidwest Holland (number 14-071), and the study was registered in the Dutch Trial Register (number NTR6566). Eligible patients who were planned to undergo a primary TKA were approached and evaluated to check if they met in- and exclusion criteria (Table 1). To have the study population represent an actual orthopaedic population, it was decided to include patients regardless of whether they had undergone previous arthroplasty in other joints or whether they mobilized using walking aids. After inclusion, all patients signed an informed consent form. All participants underwent preoperative clinical evaluations prior to their TKA and were evaluated again one year after surgery. A sample size of at least 50 patients was deemed adequate to have sufficient statistical power to detect relevant changes in gait parameters as calculated by Toebes et al.12 and to be sufficient for the correlational analysis performed. All patients received a Persona cemented total knee prosthesis (Zimmer-Biomet, Warsaw, USA). Gait quality Gait analysis was performed using the Dynaport Hybrid system (McRoberts, The Hague, The Netherlands), which uses a triaxial accelerometer for assessment in anteroposterior (AP), mediolateral (ML), and vertical (VT) direction. The accelerometer used a range from â&#x20AC;&#x201C;6 g to 6 g, with the sample rate set to 100 samples per second. The accelerometer was placed on the back of the patient at the level of the sacrum using an elastic velcro belt. To ensure that patientsâ&#x20AC;&#x2122; gait quality was optimal, measurements were done in the outpatient clinic on a level surface without distractions. Patients were then instructed to walk 2x50 meters in this setting at a self-selected pace both before and one year after the operation,

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Table 1. Study inclusion and exclusion criteria Inclusion criteria • Patient is 18 to 75 years of age. • Patient qualifies for a primary total knee arthroplasty based on physical exam and medical history, including diagnosis of severe knee pain and disability due to at least one of the following: • Rheumatoid arthritis, osteoarthritis, traumatic arthritis, polyarthritis • Collagen disorders and/or avascular necrosis of the femoral condyle • Post-traumatic loss of joint configuration, particularly when there is patellofemoral erosion, dysfunction or prior patellectomy • Moderate valgus, varus, or flexion deformities • The salvage of previously failed surgical attempts that did not include partial or total knee arthroplasty of the ipsilateral knee • Patient is willing and able to complete scheduled study procedures and follow-up evaluations Exclusion criteria • Patient is currently participating in any other surgical intervention studies or pain management studies • Previous history of infection in the affected joint and/or other local/systemic infection that may affect the prosthetic joint • Insufficient bone stock on femoral or tibial surfaces • Skeletal immaturity • Neuropathic arthropathy • Osteoporosis or any loss of musculature or neuromuscular disease that compromises the affected limb • Stable, painless arthrodesis in a satisfactory functional position • Severe instability secondary to the absence of collateral ligament integrity • Rheumatoid arthritis accompanied by an ulcer of the skin or a history of recurrent breakdown of the skin • Patient has a known or suspected sensitivity or allergy to one or more of the implant materials • Patient is pregnant • Patient is considered a member of a protected population (e.g., prisoner, mentally incompetent, etc.) • Patient has previously received partial or total knee arthroplasty for the ipsilateral knee

with a researcher monitoring them. Stride time variability (STV), low frequency percentage (LFP), gait smoothness (GS), dominant frequency amplitude (DFA), gait symmetry (harmonic ratio, HR) and stride regularity (SR) were calculated using custom MATLAB scripts (Mathworks, Natick, USA). These gait characteristics have been described previously and were successfully used before to evaluate gait quality10,13. Higher values for GS, DFA, HR and SR indicate better gait quality, whereas for STV and LFP lower values indicate better gait quality. Patients were also instructed to walk 10 meters twice whilst being timed. From this, the average walking speed in meters/second was calculated.

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PROMs Patients were asked to complete several questionnaires before surgery and one year after surgery: the Oxford Knee Score (OKS)14, which has scores ranging from 0 (best) to 48 (worst); the Knee Disability and Osteoarthritis Outcome Score (KOOS)15, which has five subscores each ranging from 0 (worst) to 100 (best) and the EQ-5D-3L, using the Dutch tariff16 with a higher score indicating higher quality of life, and included a visual analogue scale (VAS) for quality of life (QoL), ranging from 0 (worst) to 100 (best). Statistical analysis All statistical analyses were done using IBM SPSS Statistic version 23 (IBM Corporation, Armonk, NY, USA). A principal axis factor analysis was performed on the preoperative measurements, to cluster the parameters into a limited number of factors. To prevent multicollinearity in the analysis, inter-correlations were checked for r > 0.8. DFA-VT and the pain and ADL subscores of the KOOS were not entered into the factor analysis because of (multiple) inter-correlations higher than 0.8. GS-AP and DFA-AP were excluded after the individual Kaiser– Meyer–Olkin (KMO) test resulted in a value <0.5, indicating unsuitability for factor analysis. The remaining 19 outcome variables were used as input in the factor analysis. The KMO test was also used to verify the sampling adequacy considering a KMO>0.5 and Bartlett’s test of sphericity was checked for significance. The number of extracted factors was defined based on Kaiser’s criterion with eigenvalues larger than one.17 VariMax rotation was used to optimize the loading of variables onto factors. The most representative variable for each factor was used for an analysis of changes in function between measurements before and after surgery. Normality of the difference between the values of the selected outcome parameters was assessed by visual inspection of the histograms and q-q plots and using the Kolmogorov-Smirnov test. Since most differences showed a skewed distribution, differences were analyzed using non-parametric Wilcoxon signed-rank tests. To further quantify the degree of independence between PROMs and gait quality parameters, correlations between PROMs and gait quality parameters were calculated using Spearman’s Rho for baseline, 1 year postoperative and delta scores (the difference between postoperative and preoperative scores). A Spearman’s Rho value of 0.5 or higher was considered a strong association, 0.3 – 0.5 was considered moderate and 0.1 – 0.3 was considered a weak association18.

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RESULTS Study population Sixty-five patients with an average age of 65 years (range 41-75) completed the entire protocol. 54% of the patients were female, and the average BMI was 30 (range 19 to 56). Patient characteristics can be found in table 2.

Table 2. Characteristics of all included patients n=65 Age (years) at time of surgery 65 (41-75) Gender: Female 35 Male 30 BMI (kg/m2) 30 (19-56) Side for TKA Left 28 Right 37 ASA classification 1 14 2 48 3 3 Type of anesthesia Spinal/epidural 56 General 9 Duration of surgery (minutes) 66 (52-120)

Factor analysis The initial factor analysis on PROMS and gait quality parameters resulted in the identification of five factors with eigenvalues above 1.0 (>1.157), which in combination explained 62% of the variance. However, the fifth factor consisted of GS-VT only (with a factor loading of 0.550). The final factor analysis was, therefore, forced into identifying four factors, the loadings of which after Data in Mean (min-max), or number rotation are presented in Table 3. The sampling was considered adequate with a KMO of 0.744, and all individual KMO values were higher than 0.565. For this factor analysis, the lowest eigenvalue observed was 1.611 and the four factors combined explained 58% of the variance (Table 3). The four factors were defined as ‘AP/VT gait quality’, accounting for 24% of the variance, ‘PROMs’ (14%), ‘Symmetry’ (10%) and ‘ML gait quality’ (9%). The parameters having the highest factor loadings for the four factors were selected: for ‘AP/VT gait quality’, this was stride regularity-VT with a loading of -0.883, for ‘PROMs’, this was the OKS with a loading of -0.922, for ‘Symmetry’, harmonic ratio-AP with a value of 0.787, and for ‘ML gait quality’, it was stride regularity-ML with a factor loading of 0.784. Factor scores and correlations The baseline and postoperative scores of the most representative variables for each of the four factors are presented in table 4. All of these variables improved

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significantly. Correlations between the selected gait parameters and PROMs scores were calculated for the measurements before surgery, one year after surgery, and for delta values (i.e., differences between before and after surgery). Five of the nine associations were statistically significant (Table 5). Out of these five, the associations between stride regularity-VT and OKS at baseline and for delta values, and the association between stride regularity-ML and OKS for delta values were moderate (Spearmanâ&#x20AC;&#x2122;s rho values between 0.3 and 0.5). The associations between harmonic ratio-AP and the OKS at baseline and 1-year

Table 3.Rotated Factor Matrix with loading values for each parameter Factor Parameter Stride Regularity VT

1: AP/VT gait quality -0.883

2: PROMs 3: Symmetry 4: ML gait quality 0.197 0.187 0.284

Low Frequency percentage AP < 0.7 Hz

0.835

-0.137

-0.148

0.121

Walking time 10 meters

0.808

-0.175

-0.233

0.119

Low Frequency percentage VT < 0.7 Hz

0.754

-0.051

-0.179

0.133

Stride time variability

0.682

-0.251

-0.208

-0.012

Gait Smoothness (Index of Harmonicity) ML

0.535

-0.089

-0.432

-0.034

Stride Regularity AP

-0.475

0.196

0.152

0.405

Gait Smoothness (Index of Harmonicity) VT

-0.452

0.171

0.008

-0.138

Oxford Knee Score

0.293

-0.922

-0.138

0.034

KOOS QoL score

-0.123

0.758

0.065

0.023

KOOS Sport & Recreation score

-0.106

0.610

-0.032

-0.220

KOOS symptoms score

-0.208

0.596

0.143

0.047

EQ-5D

-0.039

0.459

0.164

-0.076

Gait Symmetry (Harmonic Ratio) AP

-0.234

0.143

0.787

-0.041

Gait Symmetry (Harmonic Ratio) VT

-0.232

0.119

0.715

-0.057

Gait Symmetry (Harmonic Ratio) ML

-0.099

0.111

0.623

0.177

Stride Regularity ML

-0.481

0.097

0.062

0.784

Low Frequency percentage ML < 10 Hz

0.246

-0.174

0.002

0.695

Dominant Frequencyâ&#x20AC;&#x2122;s Amplitude ML

0.204

-0.172

0.007

0.522

Eigenvalues

6.543

2.452

1.891

1.611

% of variance represented by factor

23.620

14.250

10.479

9.347

VT=vertical; ML=mediolateral; AP=anteriorposterior; QoL=quality of life;KOOS= Knee Disability and Osteoarthritis Outcome Score. Bold=included in factor; italics=excluded from factor;

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follow-up were weak (Spearman’s rho values between 0.1 and 0.3). Correlations between all gait parameters and PROMs scores can be found in Supplementary Tables 1A-C. The scores of all gait quality parameters and PROMs are presented in Supplementary Tables 2 and 3, respectively.

Table 4. This table shows the median values of the prominent variable of each factor Factor

Baseline

One year follow-up p-value

AP/VT gait quality (Stride regularity VT)

0.82 (0.15)

0.85 (0.12)

0.002

PROMs (OKS)

34 (10)

16 (9)

< 0.001

Symmetry (Harmonic ratio AP)

2.36 (1.42)

2.72 (1.11)

0.044

ML gait quality (Stride regularity ML)

0.64 (0.19)

0.69 (0.19)

0.028

Data in Median (IQR); VT=vertical; ML=mediolateral; AP=anteroposterior; PROMS=patient reported outcome measures; OKS=Oxford Knee Score

Table 5. This table shows the associations and p-values between the prominent variable of each gait quality factor and the prominent variable of the PROMs factor PROMs (OKS) Spearman’s rho (p-value)

Baseline

VT/AP gait quality (Stride regularity VT)

-0.311 (0.012)

One year follow-up -0.238 (0.060)

Delta scores

Symmetry (Harmonic ratio AP)

-0.252 (0.043)

-0.270 (0.032)

-0.071 (0.579)

ML gait quality (Stride regularity ML)

-0.239 (0.055)

-0.015 (0.909)

-0.350 (0.005)

-0.411 (0.001)

Bold = p-value 0.05 or lower. VT=vertical;ML=medial-lateral;AP=anterior-posterior; OKS=Oxford Knee Score;

DISCUSSION We performed a prospective cohort study to assess gait quality parameters in 65 patients before and one year after primary unilateral TKA and their association with (changes in) PROMs scores. To determine whether gait quality parameters contain independent information on functional outcome after TKA in addition to PROMs, and to reduce the number of variables and statistical tests, a principal factor analysis was performed. The identified factors were classified as AP/VT gait quality, PROMs, Symmetry, and ML gait quality. The most representative variable for each factor was used to evaluate the postoperative results of the TKA and this

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showed significant improvements for all factors. Correlations between gait quality parameters on one hand and PROMs on the other hand were only weak to moderate. Quality of gait was assessed using parameters that have been shown to adequately represent walking function in (elderly) populations10,13. GS, HR and SR are indicators of gait symmetry, which has been described as being an important predictive factor for falling in knee OA patients and as one aspect of gait quality which can be improved by TKA19. The gait quality parameters measured in this study showed an increased gait quality one year postoperatively, which can be expected after TKA and concurs with previous work20. A principal axis factor analysis was performed to determine which factors underlie gait quality parameters and PROMs scores that were assessed in the present study. Since gait quality analysis provides researchers with a large number of different parameters, analyzing all these parameters individually could lead to type-1 errors and a potential source of bias. Using a factor analysis to group different parameters together allows researchers to limit the bias towards a type1 error21â&#x20AC;&#x201C;23. One interesting result was that all PROMs that were included in the final factor analysis were grouped into a separate factor. This is an indication that PROMs assess a different aspect of functional outcome than gait accelerometry. This was further supported by at most weak to moderate correlations between gait quality parameters and PROMs. This lack of correlation might partially be due to PROMs scores being more correlated with pain than with functional performance4. PROMs, even though they have been repeatedly used to do so, appear not to reflect changes in function between before and after a TKA procedure adequately24,25. This suggests added value of objective performance measurements through trunk accelerometry besides using PROMs. Since accelerometers are being incorporated in modern electronics like smartphones and smart watches, these devices could potentially be used for knee OA and TKA patients in the future. This could provide physical therapists with information on which aspects of walking could be improved in individual patients, or be used by surgeons to evaluate preoperatively if a TKA is the right choice at that time for that particular patient. There were several strengths to this study. The number of patients included was relatively large for a study evaluating gait quality and PROMs in TKA patients. Several frequently used PROMs were evaluated and patients were evaluated one year after surgery. The decision to include patients with differing levels of mobility (e.g. previous arthroplasties, use of walking aids) increased the external validity of the study, because the study population more accurately represented clinical

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orthopaedic practice. However, this heterogeneity could be considered a limitation to this study. It should be taken into account when analyzing the gait quality results that these measurements were performed in a clinical setting to provide patients with a setting in which they would be able to achieve the highest level of gait quality possible. It can be expected that patients walk differently when being monitored by a researcher, which can influence gait measurements (also known as the Hawthorne effect). A further limitation was that patients were measured in a clinical setting (as mentioned above) and gait parameters were calculated over only 2x50 meters of walking. Gait analysis has been proven to become more reliable when longer periods of ambulation are analyzed26, and this would be a logical next step in research on the use of trunk accelerometry for assessing function before and after TKA. When patientâ&#x20AC;&#x2122;s ambulation could be analyzed in their domestic setting in a less standardized and controlled environment, it may have a higher predictive value for actual functioning of patients after TKA. This would also allow quantity of walking to be assessed as well as quality, which might show a better correlation with patient satisfaction as reported in the PROMs.

CONCLUSIONS Accelerometers were used to analyse gait quality in patients before and one year after primary unilateral TKA. Using a principal factor analysis, four factors were identified that represented AP/VT gait quality, PROMs, Symmetry, and ML gait quality. Correlations of gait quality parameters with PROMs were at most weak to moderate. This indicates that gait quality as assessed with accelerometers could provide additional and more detailed information on functional rehabilitation of TKA patients with objective quantifiable parameters, as a supplementary method to PROMs. Before trunk accelerometry can be used in clinical practice, further understanding of the relevance of gait quality measurements presented in this study for functioning in daily life knee OA patients is needed. Conflict of interest statement The institution of one or more of the authors has received funding from ZimmerBiomet, Mahwah, U.S.A. They did not play a role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and/or in the decision to submit the article for publication.

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Felson DT, Lawrence RC, Dieppe PA, Hirsch R, Helmick CG, Jordan JM, et al. Osteoarthritis: new insights. Part 1: the disease and its risk factors. Ann Intern Med. 2000;133:635–46. Wallace IJ, Worthington S, Felson DT, Jurmain RD, Wren KT, Maijanen H, et al. Knee osteoarthritis has doubled in prevalence since the mid-20th century. Proc Natl Acad Sci U S A. 2017;114:9332– 6. Inacio MCS, Paxton EW, Graves SE, Namba RS, Nemes S. Projected increase in total knee arthroplasty in the United States - an alternative projection model. Osteoarthr Cartil. 2017;25:1797–803. Stevens-Lapsley JE, Schenkman ML, Dayton MR. Comparison of Self-Reported Knee Injury and Osteoarthritis Outcome Score to Performance Measures in Patients After Total Knee Arthroplasty. PM&R. 2011 Jun;3:541–9. Abbasibafghi H. Thesis: Walking with Knee Osteoarthritis [Internet]. 2012. Jacobs CA, Christensen CP. Correlations between knee society function scores and functional force measures. Clin Orthop Relat Res. 2009;467:2414–9. Bolink SAAN, Grimm B, Heyligers IC. Patient-reported outcome measures versus inertial performance-based outcome measures: A prospective study in patients undergoing primary total knee arthroplasty. Knee. 2015 May 29; Kluge F, Hannink J, Pasluosta C, Klucken J, Gaßner H, Gelse K, et al. Pre-operative sensor-based gait parameters predict functional outcome after total knee arthroplasty. Gait Posture. 2018 Oct;66:194–200. van der Straaten R, De Baets L, Jonkers I, Timmermans A. Mobile assessment of the lower limb kinematics in healthy persons and in persons with degenerative knee disorders: A systematic review. Gait Posture. 2017;59:229–41. Rispens SM, Pijnappels M, van Schooten KS, Beek PJ, Daffertshofer A, van Dieën JH. Consistency of gait characteristics as determined from acceleration data collected at different trunk locations. Gait Posture. 2014 May;40:187–92. World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA. 2013 Nov 27;310:2191–4. Toebes MJP, Hoozemans MJM, Mathiassen SE, Dekker J, van Dieën JH. Measurement strategy and statistical power in studies assessing gait stability and variability in older adults. Aging Clin Exp Res. 2016 Apr 7;28:257–65. Rispens SM, Van Dieën JH, Van Schooten KS, Cofré Lizama LE, Daffertshofer A, Beek PJ, et al. Fall-related gait characteristics on the treadmill and in daily life. J Neuroeng Rehabil. 2016 Feb 2;13:12. Haverkamp D, Breugem SJM, Sierevelt IN, Blankevoort L, van Dijk CN. Translation and validation of the Dutch version of the Oxford 12-item knee questionnaire for knee arthroplasty. Acta Orthop. 2005 Jun;76:347–52. de Groot IB, Favejee MM, Reijman M, Verhaar JAN, Terwee CB. The Dutch version of the Knee Injury and Osteoarthritis Outcome Score: a validation study. Health Qual Life Outcomes. 2008;6:16. Lamers LM, McDonnell J, Stalmeier PFM, Krabbe PFM, Busschbach JJ V. The Dutch tariff: results and arguments for an effective design for national EQ-5D valuation studies. Health Econ. 2006 Oct;15:1121–32. Kaiser HF. The Application of Electronic Computers to Factor Analysis. Educ Psychol Meas. 1960 Apr 2;20:141–51. Cohen J. Statistical power analysis for the behavioural sciences. 2nd ed. 1988. Moutzouri M, Gleeson N, Billis E, Tsepis E, Panoutsopoulou I, Gliatis J. The effect of total knee arthroplasty on patients’ balance and incidence of falls: a systematic review. Knee Surg Sport Traumatol Arthrosc. 2017;25:3439–51. Senden R, Grimm B, Meijer K, Savelberg H, Heyligers IC. The importance to including objective functional outcomes in the clinical follow up of total knee arthroplasty patients. Knee. 2011;18:306–11.

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21 Toebes MJP, Hoozemans MJM, Furrer R, Dekker J, van Dieën JH. Associations between measures of gait stability, leg strength and fear of falling. Gait Posture. 2015 Jan 1;41:76–80. 22 Hollman JH, McDade EM, Petersen RC. Normative spatiotemporal gait parameters in older adults. Gait Posture. 2011 May 1;34:111–8. 23 Amboni M, Barone P, Iuppariello L, Lista I, Tranfaglia R, Fasano A, et al. Gait patterns in parkinsonian patients with or without mild cognitive impairment. Mov Disord. 2012 Oct 1;27:1536–43. 24 Naili JE, Iversen MD, Esbjornsson AC, Hedstrom M, Schwartz MH, Hager CK, et al. Deficits in functional performance and gait one year after total knee arthroplasty despite improved selfreported function. Knee Surg Sport Traumatol Arthrosc. 2017;25:3378–86. 25 Hossain FS, Konan S, Patel S, Rodriguez-Merchan EC, Haddad FS. The assessment of outcome after total knee arthroplasty: are we there yet? Bone Jt J. 2015;97-B:3–9. 26 van Schooten KS, Rispens SM, Elders PJM, van Dieën JH, Pijnappels M. Toward ambulatory balance assessment: estimating variability and stability from short bouts of gait. Gait Posture. 2014 Feb;39:695–9.

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146 -0.164 (0.196) -0.018 (0.884) 0.037 (0.773) -0.048 (0.703) -0.073 (0.564) 0.090 (0.474) 0.098 (0.436) 0.084 (0.505) -0.048 (0.703) -0.132 (294) -0.036 (776) 0.072 (0.569) -0.141 (0.262)

Walking speed meters/second

Gait Smoothness (Index of Harmonicity) ML

Gait Smoothness (Index of Harmonicity) VT

Low Frequency percentage AP < 0.7 Hz

Low Frequency percentage ML < 10 Hz

Low Frequency percentage VT < 0.7 Hz

Gait Symmetry (Harmonic Ratio) AP

Gait Symmetry (Harmonic Ratio) ML

Gait Symmetry (Harmonic Ratio) VT

Stride Regularity AP

Stride Regularity ML

Stride Regularity VT

Stride time variability (seconds)

VAS QoL

Correlation baseline Spearman’s rho 0.356 (0.004) -0.294 (0.017) 0.237 (0.057) 0.008 (0.951) -0.037 (0.767) 0.327 (0.008) 0.136 (0.278) 0.216 (0.083) -0.365 (0.003) -0.242 (0.052) -0.270 (0.030) 0.315 (0.010) -0.149 (0.236)

EQ-5D

KOOS Symptoms Pain score ADL score Sport & QoL score score Rec score 0.209 0.433 0.507 0.309 0.352 (0.097) (<0.001) (<0.001) (0.013) (0.004) -0.198 -0.396 -0.408 -0.136 -0.216 (0.114) (0.001) (0.001) (0.279) (0.084) 0.152 0.298 0.333 0.080 0.175 (0.226) (0.016) (0.007) (0.529) (0.164) 0.183 0.142 0.143 -0.027 0.186 (0.146) (0.258) (0.259) (0.833) (0.138) 0.221 0.227 0.153 0.047 0.106 (0.077) (0.069) (0.229) (0.712) (0.400) 0.158 0.303 0.309 0.289 0.198 (0.210) (0.014) (0.013) (0.020) (0.113) 0.134 0.149 0.085 0.114 0.191 (0.286) (0.238) (0.506) (0.366) (0.127) 0.136 0.286 0.260 0.175 0.100 (0.280) (0.021) (0.038) (0.164) (0.427) -0.208 -0.332 -0.322 -0.052 -0.168 (0.097) (0.007) (0.009) (0.683) (0.181) 0.004 -0.204 -0.295 -0.269 -0.122 (0.972) (0.104) (0.018) (0.031) (0.332) -0.302 -0.400 -0.406 -0.216 -0.270 (0.015) (0.001) (0.001) (0.084) (0.029) 0.026 0.254 0.289 0.239 0.234 (0.838) (0.041) (0.021) (0.056) (0.061) -0.197 -0.220 -0.227 -0.093 -0.189 (0.115) (0.078) (0.072) (0.463) (0.131)

Supplementary Table 1-A. Correlations (p-values) between gait parameters and patient reported outcome measures before surgery

-0.531 (<0.001) 0.396 (0.001) -0.311 (0.012) -0.239 (0.055) -0.126 (0.317) -0.275 (0.026) -0.279 (0.025) -0.252 (0.043) 0.359 (0.003) 0.199 (0.112) 0.501 (<0.001) -0.243 (0.051) 0.265 (0.033)

OKS

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-0.177 (0.158) 0.070 (0.581) -0.152 (0.228) -0.209 (0.094)

Gait Smoothness (Index of Harmonicity) AP

VT=vertical;ML=medial-lateral;AP=anterior-posterior

Dominant Frequency’s Amplitude AP

Dominant Frequency’s Amplitude ML

Dominant Frequency’s Amplitude VT

VAS QoL

Correlation baseline Spearman’s rho 0.234 (0.061) 0.323 (0.009) -0.125 (0.323) -0.100 (0.429)

EQ-5D

KOOS Symptoms Pain score ADL score Sport & QoL score score Rec score 0.005 -0.181 -0.282 -0.147 -0.089 (0.968) (0.148) (0.024) (0.242) (0.482) 0.042 0.294 0.327 0.221 0.163 (0.739) (0.017) (0.008) (0.076) (0.195) -0.136 -0.150 -0.222 -0.131 -0.173 (0.279) (0.234) (0.078) (0.297) (0.169) 0.149 0.044 -0.090 -0.037 0.033 (0.235) (0.725) (0.478) (0.772) (0.794) 0.270 (0.030) -0.278 (0.025) 0.131 (0.299) 0.057 (0.654)

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147

148 0.121 (0.362) -0.137 (0.278) 0.176 (0.160) 0.064 (0.610) -0.012 (0.923) 0.218 (0.081) 0.076 (0.547) 0.190 (0.129) -0.038 (0.761) -0.031 (0.804) 0.086 (0.496) 0.153 (0.223) -0.139 (0.268)

Walking speed meters/second

Gait Smoothness (Index of Harmonicity) ML

Gait Smoothness (Index of Harmonicity) VT

Low Frequency percentage AP < 0.7 Hz

Low Frequency percentage ML < 10 Hz

Low Frequency percentage VT < 0.7 Hz

Gait Symmetry (Harmonic Ratio) AP

Gait Symmetry (Harmonic Ratio) ML

Gait Symmetry (Harmonic Ratio) VT

Stride Regularity AP

Stride Regularity ML

Stride Regularity VT

Stride time variability (seconds)

VAS QoL

Correlation postoperative Spearman’s rho 0.164 (0.215) -0.168 (0.182) 0.062 (0.625) 0.042 (0.742) -0.225 (0.072) 0.198 (0.113) 0.204 (0.104) 0.170 (0.177) -0.266 (0.032) 0.013 (0.915) -0.068 (0.589) 0.088 (0.486) -0.243 (0.052)

EQ-5D

KOOS Symptoms Pain score ADL score Sport & QoL score score Rec score 0.156 0.196 0.207 0.097 0.078 (0.239) (0.141) (0.120) (0.501) (0.559) -0.090 -0.439 -0.330 -0.128 -0.200 (0.474) (<0.001) (0.008) (0.351) (0.111) 0.008 0.278 0.261 0.106 0.142 (0.947) (0.029) (00.39) (0.441) (0.260) -0.088 0.125 0.064 -0.197 0.016 (0.488) (0.334) (0.616) (0.150) (0.899) -0.190 -0.018 -0.103 -0.171 -0.169 (0.129) (0.887) (0.423) (0.213) (0.179) 0.200 0.232 0.190 0.098 0.227 (0.111) (0.070) (0.137) (0.475) (0.069) 0.120 0.013 -0.037 -0.152 0.078 (0.340) (0.920) (0.772) (0.269) (0.535) 0.250 0.278 0.262 0.214 0.311 (0.045) (0.028) (0.038) (0.117) (0.012) -0.205 -0.325 -0.236 0.011 -0.136 (0.102) (0.010) (0.063) (0.935) (0.280) -0.048 -0.119 -0.232 -0.390 -0.082 (0.703) (0.357) (0.067) (0.003) (0.516) -0.258 -0.223 -0.246 -0.063 -0.015 (0.038) (0.082) (0.052) (0.650) (0.903) 0.069 0.039 0.128 0.217 0.152 (0.584) (0.762) (0.319) (0.111) (0.226) -0.021 -0.030 -0.067 0.052 -0.077 (0.869) (0.817) (0.603) (0.705) (0.543) -0.247 (0.064) 0.376 (0.002) -0.238 (0.060) -0.015 (0.909) 0.125 (0.329) -0.269 (0.033) -0.041 (0.750) -0.270 (0.032) 0.356 (0.004) 0.286 (0.023) 0.224 (0.077) -0.134 (0.295) 0.117 (0.361)

OKS

Supplementary Table 1-B. Correlations (p-values) between gait parameters and patient reported outcome measures 1 year after surgery

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-0.068 (0.592) 0.210 (0.093) 0.077 (0.541) -0.015 (0.908)

Gait Smoothness (Index of Harmonicity) AP

VT=vertical;ML=medial-lateral;AP=anterior-posterior

Dominant Frequency’s Amplitude AP

Dominant Frequency’s Amplitude ML

Dominant Frequency’s Amplitude VT

VAS QoL

Correlation postoperative Spearman’s rho -0.068 (0.588) 0.171 (0.173) -0.047 (0.710) -0.088 (0.487)

EQ-5D

KOOS Symptoms Pain score ADL score Sport & QoL score score Rec score -0.142 -0.248 -0.306 -0.219 -0.048 (0.258) (0.052) (0.015) (0.109) (0.703) 0.150 0.192 0.225 0.182 0.242 (0.234) (0.135) (0.076) (0.184) (0.052) -0.103 -0.073 -0.046 -0.251 -0.052 (0.416) (571) (0.719) (0.065) (0.680) -0.136 -0.156 -0.253 -0.171 -0.018 (0.282) (0.226) (0.045) (0.212) (0.889) 0.209 (0.100) -0.233 (0.067) 0.164 (0.200) 0.157 (0.220)

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149

150 0.153 (0.252) 0.105 (0.403) 0.053 (0.673) -0.096 (0.448) -0.130 (0.301) -0.100 (0.426) 0.045 (0.724) -0.112 (0.376) -0.058 (0.648) -0.022 (0.865) 0.092 (0.013) 0.039 (0.759)

Walking speed meters/second

Gait Smoothness (Index of Harmonicity) VT

Low Frequency percentage AP < 0.7 Hz

Low Frequency percentage ML < 10 Hz

Low Frequency percentage VT < 0.7 Hz

Gait Symmetry (Harmonic Ratio) AP

Gait Symmetry (Harmonic Ratio) ML

Gait Symmetry (Harmonic Ratio) VT

Stride Regularity AP

Stride Regularity ML

Stride Regularity VT

Stride time variability (seconds)

VAS QoL

Correlation delta scores Spearman’s rho 0.251 (0.057) -0.184 (0.143) 0.314 (0.011) 0.199 (0.112) -0.066 (0.599) 0.193 (0.124) 0.131 (0.298) 0.146 (0.244) -0.279 (0.025) -0.002 (0.987) -0.158 (0.208) 0.239 (0.055)

EQ-5D

KOOS Symptoms Pain score ADL score Sport & QoL score score Rec score 0.147 0.222 0.330 0.175 0.275 (0.270) (0.097) (0.012) (0.229) (0.037) -0.200 -0.329 -0.370 -0.161 -0.184 (0.110) (0.009) (0.003) (0.239) (0.142) 0.202 0.255 0.283 0.303 0.316 (0.106) (0.046) (0.026) (0.025) (0.010) 0.178 0.088 0.221 0.185 0.188 (0.156) (0.498) (0.085) (0.176) (0.134) 0.149 0.061 0.027 0.046 0.046 (0.237) (0.640) (0.834) (0.738) (0.716) 0.184 0.214 0.257 0.129 0.184 (0.143) (0.095) (0.044) (0.349) (0.141) 0.154 -0.022 0.096 0.076 0.176 (0.221) (0.866) (0.459) (0.580) (0.161) 0.055 0.050 0.139 0.052 0.197 (0.666) (0.700) (0.283) (0.707) (0.115) -0.145 -0.146 -0.258 -0.186 -0.076 (0.249) (0.257) (0.043) (0.173) (0.549) 0.007 -0.071 -0.113 -0.023 0.032 (0.956) (0.585) (0.384) (0.865) (0.800) -0.306 -0.223 -0.269 -0.211 -0.252 (0.013) (0.081) (0.035) (0.122) (0.043) -0.139 0.016 0.015 0.194 -0.002 (0.269) (0.905) (0.908) (0.156) (0.986) -0.301 (0.024) 0.418 (0.001) -0.411 (0.001) -0.350 (0.005) -0.097 (0.450) -0.277 (0.028) -0.118 (0.358) -0.071 (0.579) 0.211 (0.096) 0.059 (0.647) 0.341 (0.006) -0.045 (0.726)

OKS

Supplementary Table 1-C. Correlations (p-values) between delta scores (postoperative scores minus baseline score) of gait parameters and patient reported outcome measures

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-0.126 (0.319) 0.049 (0.701) 0.036 (0.777) -0.082 (0.515) -0.114 (0.364)

Gait Smoothness (Index of Harmonicity) ML

VT=vertical;ML=medial-lateral;AP=anterior-posterior

Dominant Frequency’s Amplitude AP

Dominant Frequency’s Amplitude ML

Dominant Frequency’s Amplitude VT

Gait Smoothness (Index of Harmonicity) AP

VAS QoL

Correlation delta scores Spearman’s rho -0.078 (0.535) -0.223 (0.075) 0.308 (0.013) 0.218 (0.081) -0.182 (0.147)

EQ-5D

KOOS Symptoms Pain score ADL score Sport & QoL score score Rec score -0.259 -0.311 -0.295 -0.198 -0.198 (0.037) (0.014) (0.020) (0.148) (0.113) -0.098 -0.067 -0.169 -0.119 -0.128 (0.439) (0.603) (0.189) (0.386) (0.309) -0.023 0.144 0.140 0.315 0.168 (0.853) (0.264) (0.277) (0.019) (0.182) 0.071 0.134 0.185 0.166 0.032 (0.574) (0.301) (0.151) (0.226) (0.799) -0.068 -0.106 -0.190 -0.038 -0.041 (0.592) (0.414) (0.138) (0.786) (0.743) 0.243 (0.055) 0.168 (0.189) -0.218 (0.086) -0.137 (0.285) 0.133 (0.297)

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Supplementary Table 2. Gait parameter scores with p-values Stride time variability (seconds) Stride Regularity VT Stride Regularity ML Stride Regularity AP Gait Symmetry (Harmonic Ratio) VT Gait Symmetry (Harmonic Ratio) ML Gait Symmetry (Harmonic Ratio) AP Low Frequency percentage VT < 0.7 Hz Low Frequency percentage ML < 10 Hz Low Frequency percentage AP < 0.7 Hz Gait Smoothness (Index of Harmonicity) VT Gait Smoothness (Index of Harmonicity) ML Gait Smoothness (Index of Harmonicity) AP Dominant Frequency’s Amplitude VT Dominant Frequency’s Amplitude ML Dominant Frequency’s Amplitude AP Walking speed meters/second

Baseline 0.03 (0.02) 0.82 (0.15) 0.64 (0.19) 0.76 (0.14) 2.82 (1.40) 2.19 (1.26) 2.36 (1.42) 0.02 (0.02) 90.23 (12.99) 0.62 (0.92) 0.73 (0.16) 0.15 (0.29) 0.66 (0.21) 0.80 (0.28) 0.34 (0.29) 0.63 (0.24) 1.05 (026)

One year follow-up 0.02 (0.01) 0.85 (0.12) 0.69 (0.19) 0.74 (0.18) 3.28 (1.40) 2.33 (1.13) 2.72 (1.11) 0.01 (0.01) 88.31 (9.14) 0.45 (0.50) 0.74 (0.15) 0.12 (0.16) 0.60 (0.23) 0.87 (0.22) 0.35 (0.32) 0.54 (0.26) 1.23 (0.28)

Data in Median (IQR); VT=vertical; ML=mediolateral; AP=anteroposterior; Hz=Hertz

152

p-value 0.001 0.002 0.028 0.572 0.294 0.119 0.044 < 0.001 0.184 0.002 0.023 0.151 < 0.001 0.002 0.148 0.011 < 0.001

GAIT QUALITY AND ITS ASSOCIATION WITH PROMS

Supplementary Table 3. PROMs scores with p-values VAS QoL EQ-5D KOOS Symptoms score Pain score ADL score Sport & Recreation score QoL score OKS

Baseline 70 (15) 0.78 (0.44) 54 (21) 44 (24) 49 (23) 10 (25) 25 (19) 34 (10)

One year follow-up 80 (14) 0.90 (0.19) 82 (18) 94 (15) 94 (15) 60 (45) 75 (34) 16 (9)

p-value < 0.001

< 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001

Data in Median (IQR); VAS=visual analogue scale; QoL=quality of life; OKS= Oxford Knee Score; KOOS= Knee Disability and Osteoarthritis Outcome Score

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CHAPTER 7 Patientsâ&#x20AC;&#x2122; daily-life gait quality, gait behavior, and perceived walking abilities before and 3 months after total knee arthroplasty

Manuscript in preparation BL Fransen, M Pijnappels, IK Butter, BJ Burger, JH van DieĂŤn, MJM Hoozemans

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ABSTRACT Introduction Functional outcome after total knee arthroplasty (TKA) is becoming more important with an increasingly younger and more active patient population, with increasing emphasis on patients’ daily-life activities. Trunk-based accelerometers have shown to be a possible assistive method of evaluating gait function after TKA, besides patient reported outcome measures (PROMs). The aim of this study was to use PROMs and trunk-based accelerometers to evaluate perceived walking abilities, daily-life gait behavior, and daily-life gait quality of patients before and 3 months after TKA. Patients and methods A prospective cohort study of 38 patients (mean age 68.7, min-max 58-83 years) completed questionnaires including the Oxford Knee Score (OKS) and modified Gait Efficacy Scale (mGES) before and three months after primary unilateral TKA surgery. At both time points, they wore a trunk-based tri-axial accelerometer for seven consecutive days and nights. Gait behavior was calculated using gait quantity and walking speed, and multiple gait quality parameters were calculated. Results Significant improvements were seen after three months in the OKS (med(IQR) 29(10) vs 38.5(8), p=<.001) and perceived walking abilities as measured with mGES (median(IQR) 67(24) vs 79(25), p-value .001). No significant improvements were seen in gait behavior (quantity and speed) or gait quality variables. Discussion Contrary to the significant improvements of patients’ perception of their walking abilities and their PROMs scores, patients did not show similar improvements in gait behavior and gait quality three months after primary unilateral TKA. This implies that patients’ functional and perceived abilities after TKA do not necessarily represent their actual daily-life quantity and quality of gait, and that more focus is needed in postoperative rehabilitation on improving gait and domestic functional behavior.

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INTRODUCTION Total knee arthroplasty (TKA) is a successful method to treat end-stage osteoarthritis (OA) of the knee. With increasing numbers of TKA procedures performed, a more active older population, and patients undergoing TKA surgery at a relatively younger age, functional outcome after TKA has become increasingly relevant.1 Particularly, gait function in terms of gait quality (e.g. speed, variability) and amount of ambulation appear as important indicators for changes in physical functioning in patients with knee OA and after TKA.2 These changes in gait quality and amount of walking are important, since a lower quality of gait has been associated with falling,3 and a decreased gait speed with depression,4 disability,5 and even mortality.6 Patient Reported Outcome Measures (PROMs), which are commonly used to quantify surgical outcome, appear not to be highly correlated with objective measures of (gait) function .7,8 Moreover, functional measures are usually assessed in a clinical setting, and earlier studies have found discrepancies between gait measurements in an optimal clinical setting and what patients are able to achieve in daily life at home.9–12 Therefore, clinical function measurements may not be representative for daily life gait behavior and patient’s perception may differ from how well they actually walk, especially in older adults who still constitute the largest group of patients with a TKA.13 Therefore, to fully capture functional outcome, there is a need for additional methods of measuring daily-life gait quality and quantity after TKA, allowing differentiation between patients’ perception of their gait function and their actual behavior. The use of accelerometers, a type of inertial measurement units, is currently emerging as an assistive tool to objectively quantify ambulation of TKA patients. It allows for both instrumented testing of functional performance in a controlled setting, and for monitoring and quantification of the amount and quality of daily life activities.14,15 Accelerometry measurements are commonly obtained in clinical and optimal settings as well as in a domestic setting, where the former can provide an objective indication of functional abilities, whereas the latter gives an impression of functional daily life behavior.9 In an earlier study, we found significant improvements in several gait quality parameters (stride regularity and symmetry) using trunk-based accelerometers in small bouts of gait in a controlled setting.16 Larger numbers of steps and longer bouts of walking increase the reliability of the instrumented gait measures.17,18 Ideally therefore, TKA patients should be monitored for a longer period of time in a domestic setting, to obtain objective and reliable measures of the quantity and quality of their daily life gait. One week measurements with trunk-based accelerometers have shown to be a reliable

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method of quantifying gait quality and behavior in other populations such as healthy older adults19 and stroke survivors.20 In this prospective observational cohort study, we therefore aimed to use trunk-based accelerometry to explore whether and how much knee OA patients’ daily life gait quality (stride regularity and symmetry), gait behavior (gait quantity and speed), and patients’ perception on their own walking abilities change both before and after TKA. These outcomes could contribute to a better understanding of functional outcome after TKA.

PATIENTS & METHODS Study design A prospective observational cohort study was performed in a large teaching hospital between 1 October 2017 and 30 November 2018. Institutional Review Board approval was received from the Medical Ethical Committee Noord-Holland (number M017.011). Patients were approached via telephone and asked to participate in the study. They then received the informed consent form through mail (which they completed before starting measurements) together with the accelerometer and questionnaires. They were asked to wear the accelerometer on their lower back for one week, day and night, except during aquatic activities such as showering. Patients wore the accelerometer and completed questionnaires before surgery and three months after surgery. This follow-up moment was chosen, since at three months almost all patients are expected to have recovered to a level close to their final functional level.21 Similarly, in total hip arthroplasty (THA) patients, most gain in gait function as measured with accelerometers was found in the first three months after surgery.22 Study population Patients who were on the waiting list for a primary TKA were eligible for inclusion. To increase external validity, we decided to include all patients who were ambulatory and willing to cooperate with study requirements regardless of comorbidity. Using G*Power, (Heinrich-Heine-University, Dusseldorf, Germany)23 a population of 30-50 patients was deemed sufficient to determine a medium sized effect of 0.5 on instrumented gait quality measures, with a correlation between repeated measures of r=0.6, based on a power of 0.8 and a p-value of 0.05.24 All patients’ general characteristics like age, gender, body heights, body mass index (BMI), smoking status, and American Society of Anesthesiologists (ASA) classification were collected from their patient files.

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TKA Procedure All patients received a Genesis II fixed bearing total knee prosthesis (Smith & Nephew, London, United Kingdom), with a fast-track protocol with local infiltration anesthesia, early mobilization and short acting opiates only when necessary. Patients were discharged home when they were able to ambulate independently with crutches or other walking aids, or were discharged to a rehabilitation center. They were prescribed a standard physical therapy regimen, which they performed with their own physical therapist. Assessment of gait function To evaluate patients’ gait behavior before and after TKA, three aspects of gait were analyzed: patients’ perception about their own walking abilities, gait behavior (quantity and speed), and gait quality (regularity and symmetry). For quantification of patients’ perception of gait, we used The Dutch version of the modified Gait Efficacy Scale (mGES).25 It comprises 10 questions about daily walking tasks, with patients indicating how confident they feel on executing each task on a scale from 1 to 10 points. The total score ranges from 0 to 100, with 100 indicating full confidence in all tasks. Additionally, patients were asked to complete a questionnaire before surgery and 3 months postoperatively, including the nationwide used PROMs. This included a numeric rating scale (NRS) for pain, the short version of the Knee Osteoarthritis Outcome Scale (KOOS-PS)26, EuroQol 5D (EQ-5D)27, Oxford Knee Score (OKS)28, and the High Activity Arthroplasty Score (HAAS)29. Daily life physical activity was assessed during 7 consecutive days using a tri-axial trunk-worn accelerometer (MoveMonitor, McRoberts, The Hague, The Netherlands). All patients received standardized written instructions on how to wear the device. Accelerations were measured in 3 directions: anterior-posterior (AP), medial-lateral (ML), and vertical (VT), using a range from –6 g to 6 g, with the sample rate set to 100 samples/s. Patients were instructed to wear the device at their lower back at the level of the fifth lumbar vertebrae using a Velcro belt. Accelerometer data were analysed using MATLAB (Mathworks, Natick, USA). We used previously validated algorithms20 to determine epochs of 8 seconds or more in which continuous gait was detected. To express gait behavior, first the average number of 8-second epochs per day that the accelerometer was worn was calculated as the amount of gait. If patients reported they had inadvertently been unable to wear the accelerometer for the whole week, the actual number of days the device was worn was noted and the number of epochs per day corrected. Second, gait speed was calculated from

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the accelerometer data by using the leg length of patients (calculated as 53% from their body height30). This value was reported in meters per second. To quantify gait quality, we accumulated data of the epochs of gait and calculated gait characteristics in AP, ML and VT direction.3 Median values and interquartile range (IQR) of each of these characteristics over all 8-second epochs were obtained over one-week measurements. In a previous study, in which we assessed instrumented gait function of TKA patients in a controlled setting, we established three factors representing three different, most prominent aspects of gait quality in TKA patients: AP/VT gait quality, ML gait quality, and Symmetry.16 Therefore, in the current study we calculated the most representative variable of each of these three factors (stride regularity-VT for AP/VT gait quality, stride regularity-ML for ML gait quality, and harmonic ratio-AP for symmetry) for each of the 8 seconds epochs of daily-life gait. Because of the longer bouts of ambulation in the current study, additional gait quality parameters that describe the dynamic regularity and stability of the gait quality data could be calculated that were not used in the previous study: sample entropy31 (SE) and the local divergence exponents (LDE)32 calculated using the methods described by Wolf33 and Rosenstein34. Statistical analysis Statistical analysis was done using IBM SPSS statistics, version 23 (IBM, Armonk, USA). For all questionnaire, gait behavior, and gait quality variables, the normality of the differences between the two assessments was checked by visual inspection of their q-q plot and box plot. A Shapiro-Wilks test was carried out on the differences. If the differences were from a normally distributed population, a paired t-test was used to determine if there was a significant difference between the two assessments. If the differences were not from a normal distribution, a Wilcoxon signed-rank test was used to determine if there was a significant difference between the two measurements. To reduce the chance of a type I error by testing all 27 gait quality variables, for each aspect of gait quality only the abovementioned 3 key variables (stride regularity-VT for AP/VT gait quality, stride regularity-ML for ML gait quality, and harmonic ratio-AP for symmetry) were tested for statistical differences. The gait quality parameters that were not included in the principal factor analysis of the previous study (SE and LDE) were also tested seperately.

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RESULTS Study population After being approached by phone, 50 patients agreed to participate in the study and completed the informed consent form. Out of these, a total of 38 patients completed the entire protocol and were included in the analysis. All patient characteristics are reported in Table 1, and a flow chart of the inclusion of the study population is shown in Figure 1. Of the 12 patients that did not complete the protocol, five were due to one missing gait assessment due to a device malfunction, four patients had their surgery postponed or cancelled, two patients did not want to partake in follow-up measurements, and one patient did not receive the accelerometer due to logistical problems with the mail. Of the five device malfunctions, three patients had a corrupt file on their device which could not be analysed, and two patients returned a device that was missing the data file altogether.

Table 1. Patient characteristics Age (years) BMI (kilogram/meter2) Gender Female Male ASA classification 1 2 3 4 TKA Side Left Right

Mean 68.7 28.7 Number (%) 18 (47.4) 20 (52.6) 4 (10.5) 28 (73.7) 6 (15.8) 0 (0) 14 (36.8) 24 (63.2)

Min 58 22

Max 83 35.6

SD 7.1 3.7

Gait function Patients’ perceived ability of gait function was measured with the mGES and PROMs questionnaires. mGES showed a significant increase after three months (median(IQR) 67(24) vs 79(25), p-value .001), indicating that patients felt more confident in their walking tasks after TKA. The postoperative score on OKS

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Figure 1. Flow chart of study population

showed a statistically significant increase (med(IQR) 29(10) vs 38.5(8), p=<.001) which indicated better outcome after surgery as reported by patients themselves. When looking at gait behavior, quantity of gait as measured with the median number of epochs per day was four epochs higher after three months, which was not a statistically significant difference (med(IQR) 218.86(178.5) vs 222.71 (122.76), p=.421). Also, there was no significant difference in gait speed between before surgery and three months after surgery (med(IQR) 0.85(0.03) vs 0.79(.013) meter/ second, p=.126). Of the three key gait quality variables and the dynamic stability measures (SE and LDE) that were statistically tested, none showed statistically significant differences between the baseline and postoperative measurements (Table 2). Values before and after TKA of all questionnaire, gait behavior, and daily life gait quality measures are presented in Supplementary table 1.

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Table 2. Results of statistical tests of key variables Perceived ability mGES (0-100) PROMs (OKS (0-48)) Gait behavior Quantity (Number of 8 second epochs per day) Gait speed (meters/second) Gait quality Factors AP/VT gait quality (stride regularity-VT) ML gait quality (stride regularity-ML) Symmetry (harmonic ratio-AP) Additional parameters Sample Entropy VT Sample Entropy ML Sample Entropy AP Local Divergence Exponent Wolf VT (s-1) Local Divergence Exponent Wolf ML (s-1) Local Divergence Exponent Wolf AP (s-1) Local Divergence Exponent Rosenstein VT (s-1) Local Divergence Exponent Rosenstein ML (s-1) Local Divergence Exponent Rosenstein AP (s-1)

Baseline

3 months follow-up

p-value

67 (24) 29 (9.5)

79 (25) 38.5 (8.25)

.001 <.001

218.86 (178.50) 0.85 (0.03)

222.71 (122.76) 0.79 (0.13)

.421 .126

0.52 (0.14) 0.42 (0.10) 1.27 (0.21)

0.50 (0.12) 0.44 (0.12) 1.25 (0.18)

.868 .073 .607

0.23 (0.06) 0.30 (0.07) 0.26 (0.06) 1.60 (0.25) 1.74 (0.24) 1.70 (0.20) 0.78 (0.14) 0.66 (0.09) 0.67 (0.11)

0.23 (0.08) 0.31 (0.05) 0.26 (0.06) 1.65 (0.22) 1.70 (0.25) 1.64 (0.23) 0.79 (0.15) 0.66 (0.14) 0.65 (0.09)

.091 .936 .856 .658 .086 .086 .226 .845 .081

Data in Median (IQR); VT=vertical; ML=medial-lateral; AP=anterior-posterior; mGES=modified Gait Efficacy Scale; PROMs=patient reported outcome measures; OKS=Oxford Knee Score

DISCUSSION We followed a cohort of 38 patients undergoing primary TKA prospectively with the aim of examining patients’ perceived walking abilities, gait behavior, and gait quality in a daily-life, domestic setting up to three months after surgery, using trunk-based accelerometry. Data were collected on gait behavior (gait quantity and walking speed) and gait quality using instrumented gait measurements with accelerometers for 7 days, and data on patients’ perceived abilities using several PROMs. We found that even though patients’ perception about their walking abilities and their OKS scores generally improved, this was not reflected in objective measures of the quantity and quality of daily-life gait function.

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PROMs and perceived walking abilities Both the OKS and mGES showed significant increases three months after surgery, indicating that patients subjectively reported that the outcome of their surgery was beneficial, and reflected an improvement of their gait efficacy. Earlier research suggested that an increased score on the mGES can be predictive of physical activity after TKA.35 Therefore, the fact that in the current study patients did neither increase amount, nor speed of walking, nor improve their gait quality, is contradictory to those findings and implies that patients did not alter their gait behavior after surgery, even with more confidence in walking. It is feasible that once back home after their hospital stay, patients continued their old behavioral patterns of walking. This could be a target for postoperative rehabilitation, and provides an argument that more attention for the behavioral/perceptual aspects of patientsâ&#x20AC;&#x2122; rehabilitation after TKA is needed to supplement the functional training aimed at range of motion and muscle strength. Gait behavior In contrast to our expectations, the average number of walking epochs per day did not significantly increase in our patients. Similarly, other studies also did not find any changes in physical activity levels after TKA, after one month in the amount of steps15, after six months in the average amount of activity36, and even at almost two years after TKA surgery in the average amount or intensity of activity.37 When compared to healthy age-matched control patients, TKA patients appear to remain below or at most at similar levels of activity.38 One research group found a minor increase in physical activity 6 months after TKA39, but after four years in a follow-up study patients were actually less active even though they too reported an increased perceived ability.40 There are indications that quantity of walking is correlated with patient satisfaction after TKA.41 The fact that gait quantity does not improve in the first three months after TKA surgery could therefore be considered a possible target for increasing satisfaction rates in TKA patients. However, as patient satisfaction is strongly associated with other factors42, the effect of increasing gait quantity on improving patient satisfaction is probably limited. Gait speed did not change significantly after surgery in the present study. The fact that patients do not walk faster after TKA is surprising and very relevant, since an higher gait speed has been associated with better gait quality and a lower in the risk of falling.43 Furthermore, lower gait speed has even been shown to be a predictive factor in patientsâ&#x20AC;&#x2122; hazard ratio on mortality.6 Since targeted therapy can help patients achieve higher gait speeds44, postoperative rehabilitation after TKA could help to address lack of increase in gait speed found in this study.

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Gait quality Our previous study using trunk-based accelerometers showed significant improvements in gait quality parameters one year after TKA in a controlled setting.16 In contrast to what would be expected based on these results as well as TKA outcome measured with PROMs21, three months after surgery the gait quality variables tested in the current study did not show statistically significant differences compared to baseline. One explanation for these findings could be that gait quality measured with accelerometers differs between a controlled clinical setting and daily life gait.9 This raises the question whether studies that evaluate gait quality only in a clinical setting assess improvement of function and performance in optimal circumstances, and/or whether patients are motivated to perform better after surgery when observed by surgeons or researchers. Unfortunately, for this study we were not able to collect both clinical and daily-life measurements of the same patients to answer this question. For future studies, it would be interesting to have gait quality measurements of the same patients both in a clinical setting and in a daily life domestic setting at three months and one year after surgery. If there is indeed a discrepancy between the clinical and domestic setting, demonstrating this to patients could provide treating physicians and therapists with a way to motivate patients to walk more and better in their home environment. Another reason for the lack of significant differences in gait quality variables could be that patients have altered their walking behavior during their time suffering from knee OA, and that three months is not enough for patients to significantly readjust their behavior and thereby their gait quality (and quantity) in daily-life. In contrast to positive effects on gait function three months after THA22, there are other studies that also found insufficient or no improvement of gait quality three months after TKA. For example, Alice and coworkers found that knee function and gait velocity had not improved to satisfactory levels three months after TKA as measured with 3D motion analysis in a clinical setting.45 Strengths and limitations A strength of our study was the high reliability of the daily life gait characteristics, as patients wore the accelerometers at home day and night for seven days. The consensus among other studies was that increasing the bouts of gait and, thereby, the number of steps measured, increases the reliability of the gait parameters.17,18 Second, external validity was increased through including a heterogeneous sample of patients that had an indication for primary unilateral TKA. Although comorbidities (e.g. OA in the contralateral leg) could have introduced bias, this is also the case in a general orthopaedic population and earlier studies did not

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find that comorbidities influenced accelerometer data in TKA patients.37 Both strengths make the data representative for everyday gait function of patients before and after TKA.9 However, this study also had some limitations. We added several gait quality parameters that were not part of the factor analysis of our previous study, possibly increasing the chance of a type I error. However, since the changes in these parameters did also not show a statistically significant difference, this does not seem to be the case. Several patients (n=12: 24%) did not complete the protocol, because of device malfunctions, logistical difficulties, postponed surgeries and/ or refusal of follow-up measurements. We could not find a pattern in which patients declined to finish the protocol, and it does therefore not appear to influence the generalisability of our results. Of three patients, it was not possible to analyse the accelerometry data. It appears that patients wore the device inadequately, despite explicit instructions on how to wear the device. This could also be considered a strength, since the vast majority of patients used the device in the correct way. For future studies, this might be prevented through the use of a smartphone app, comparable to what is already used in improving efficacy and compliance of training programs after TKA.46 However, algorithms are yet inaccurate to validly and reliably calculate gait quality measures and gait speed from smartphone data, mostly because of the large variation in the way smartphones are carried with respect to the body.

CONCLUSION Our study showed that despite significant improvements of patientsâ&#x20AC;&#x2122; perception of their walking abilities and their PROMs scores three months after primary unilateral TKA, their daily life gait behavior in terms of gait quantity, speed, and gait quality did not change. The results of this study suggest that caretakers should be aware that patientsâ&#x20AC;&#x2122; clinically assessed functional and perceived abilities after TKA are not necessarily representative of their actual daily activities, and vice versa. This indicates that if orthopaedic surgeons want to know how well patients function at home after TKA, objective measurements are needed to add to the data gathered using PROMs. Additionally, these results imply that improvements in quality, quantity and speed of walking after TKA could be achievable by increasing the focus of postoperative rehabilitation after TKA on improving gait and gait behavior in their domestic environment.

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REFERENCES 1. Inacio MCS, Paxton EW, Graves SE, Namba RS, Nemes S. Projected increase in total knee arthroplasty in the United States - an alternative projection model. Osteoarthr Cartil. 2017/08/13. 2017; 25: 1797–803. 2. Clermont CA, Barden JM. Accelerometer-based determination of gait variability in older adults with knee osteoarthritis. Gait Posture . 2016; 50: 126–30. 3. van Schooten KS, Pijnappels M, Rispens SM, Elders PJM, Lips P, van Dieën JH. Ambulatory FallRisk Assessment: Amount and Quality of Daily-Life Gait Predict Falls in Older Adults. Journals Gerontol Ser A Biol Sci Med Sci . 2015; 70: 608–15. 4. White DK, Neogi T, Zhang Y, Niu J, Katz PP. Association of Slow Gait Speed With Trajectories of Worsening Depressive Symptoms in Knee Osteoarthritis: An Observational Study. Arthritis Care Res (Hoboken) . 2017; 69: 209–15. 5. Perera S, Patel K V., Rosano C, et al. Gait Speed Predicts Incident Disability: A Pooled Analysis. Journals Gerontol Ser A Biol Sci Med Sci . 2016; 71: 63–71. 6. Studenski S, Perera S, Patel K, et al. Gait speed and survival in older adults. JAMA . 2011/01/06. 2011; 305: 50–8. 7. Stevens-Lapsley JE, Schenkman ML, Dayton MR. Comparison of Self-Reported Knee Injury and Osteoarthritis Outcome Score to Performance Measures in Patients After Total Knee Arthroplasty. PM&R . 2011; 3: 541–9. 8. Luna IE, Kehlet H, Peterson B, Wede HR, Hoevsgaard SJ, Aasvang EK. Early patient-reported outcomes versus objective function after total hip and knee arthroplasty. Bone Joint J . 2017; 99-B: 1167–75. 9. Rispens SM, Van Dieën JH, Van Schooten KS, et al. Fall-related gait characteristics on the treadmill and in daily life. J Neuroeng Rehabil. 2016; 13: 12. 10. Van Ancum JM, van Schooten KS, Jonkman NH, et al. Gait speed assessed by a 4-m walk test is not representative of daily-life gait speed in community-dwelling adults. Maturitas . 2019; 121: 28–34. 11. Hiyama Y, Asai T, Wada O, et al. Gait variability before surgery and at discharge in patients who undergo total knee arthroplasty: a cohort study. PLoS One . 2015; 10: e0117683. 12. Christiansen CL, Bade MJ, Paxton RJ, Stevens-Lapsley JE. Measuring movement symmetry using tibial-mounted accelerometers for people recovering from total knee arthroplasty. Clin Biomech . 2015; 30: 732–7. 13. Delbaere K, Close JCT, Brodaty H, Sachdev P, Lord SR. Determinants of disparities between perceived and physiological risk of falling among elderly people: cohort study. BMJ . 2010; 341: c4165. 14. van Lummel RC, Walgaard S, Pijnappels M, et al. Physical Performance and Physical Activity in Older Adults: Associated but Separate Domains of Physical Function in Old Age. Reddy H, editor. PLoS One . 2015; 10: e0144048. 15. Schotanus MGM, Bemelmans YFL, Grimm B, Heyligers IC, Kort NP. Physical activity after outpatient surgery and enhanced recovery for total knee arthroplasty. Knee Surgery, Sport Traumatol Arthrosc . 2017; 25(11):3366-3371 16. Fransen B, Mathijssen NMC, Slot K, et al. Gait quality assessed by trunk accelerometry after total knee arthroplasty and its association with patient reported outcome measures. Clin Biomech. 2019; submitted. 17. van Schooten KS, Rispens SM, Elders PJM, van Dieën JH, Pijnappels M. Toward ambulatory balance assessment: estimating variability and stability from short bouts of gait. Gait Posture . 2014; 39: 695–9. 18. Hollman JH, Childs KB, McNeil ML, Mueller AC, Quilter CM, Youdas JW. Number of strides required for reliable measurements of pace, rhythm and variability parameters of gait during normal and dual task walking in older individuals. Gait Posture . 2010; 32: 23–8. 19. Rispens SM, Pijnappels M, van Schooten KS, Beek PJ, Daffertshofer A, van Dieën JH. Consistency of gait characteristics as determined from acceleration data collected at different trunk locations. Gait Posture . 2014; 40: 187–92.

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20. Punt M, Bruijn SM, van Schooten KS, et al. Characteristics of daily life gait in fall and non fallprone stroke survivors and controls. J Neuroeng Rehabil . 2016; 13: 67. 21. Neuprez A, Neuprez AH, Kaux J-F, et al. Early Clinically Relevant Improvement in Quality of Life and Clinical Outcomes 1 Year Postsurgery in Patients with Knee and Hip Joint Arthroplasties. Cartilage . 2018; 9: 127–39. 22. Bolink SAAN, Lenguerrand E, Brunton LR, et al. Assessment of physical function following total hip arthroplasty: Inertial sensor based gait analysis is supplementary to patient-reported outcome measures. Clin Biomech. 2016; 32:171-179 23. Faul F, Erdfelder E, Lang A-G, Buchner A. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods . 2007; 39: 175–91. 24. Toebes MJP, Hoozemans MJM, Mathiassen SE, Dekker J, van Dieën JH. Measurement strategy and statistical power in studies assessing gait stability and variability in older adults. Aging Clin Exp Res . 2016; 28: 257–65. 25. Newell AM, VanSwearingen JM, Hile E, Brach JS. The modified Gait Efficacy Scale: establishing the psychometric properties in older adults. Phys Ther . 2012; 92: 318–28. 26. Perruccio A V, Stefan Lohmander L, Canizares M, et al. The development of a short measure of physical function for knee OA KOOS-Physical Function Shortform (KOOS-PS) - an OARSI/ OMERACT initiative. Osteoarthr Cartil . 2008; 16: 542–50. 27. Lamers LM, McDonnell J, Stalmeier PFM, Krabbe PFM, Busschbach JJ V. The Dutch tariff: results and arguments for an effective design for national EQ-5D valuation studies. Health Econ . 2006; 15: 1121–32. 28. Haverkamp D, Breugem SJM, Sierevelt IN, Blankevoort L, van Dijk CN. Translation and validation of the Dutch version of the Oxford 12-item knee questionnaire for knee arthroplasty. Acta Orthop . 2005; 76: 347–52. 29. Fransen BL, Kan HJ, Posthuma de Boer J, Burger BJ, Hoozemans MJM. Cross-cultural adaptation and validation of the Dutch version of the High Activity Arthroplasty Score. Ned Tijdschr voor Orthop . 2018; 25: 68–74. 30. Judge JO, Davis RB, Ounpuu S. Step length reductions in advanced age: the role of ankle and hip kinetics. J Gerontol A Biol Sci Med Sci . 1996; 51: M303-12. 31. McCamley JD, Denton W, Arnold A, Raffalt PC, Yentes JM. On the calculation of sample entropy using continuous and discrete human gait data. Entropy (Basel) . NIH Public Access; 2018; 20. 32. Rispens SM, Pijnappels M, Van Dieën JH, Van Schooten KS, Beek PJ, Daffertshofer A. A benchmark test of accuracy and precision in estimating dynamical systems characteristics from a time series. J Biomech. 2014; 47(2):470-5 33. Wolf A, Swift JB, Swinney HL, Vastano JA. Determining Lyapunov exponents from a time series. Phys D Nonlinear Phenom . 1985; 16: 285–317. 34. Rosenstein MT, Collins JJ, De Luca CJ. A practical method for calculating largest Lyapunov exponents from small data sets. Phys D Nonlinear Phenom . 1993; 65: 117–34. 35. Taniguchi M, Sawano S, Kugo M, Maegawa S, Kawasaki T, Ichihashi N. Physical Activity Promotes Gait Improvement in Patients With Total Knee Arthroplasty. J Arthroplasty . 2016; 31: 984–8. 36. Harding P, Holland AE, Delany C, Hinman RS. Do Activity Levels Increase After Total Hip and Knee Arthroplasty? Clin Orthop Relat Res . 2014; 472: 1502. 37. Kahn TL, Schwarzkopf R. Does Total Knee Arthroplasty Affect Physical Activity Levels? Data from the Osteoarthritis Initiative. J Arthroplasty . 2015; 30: 1521–5. 38. Paxton RJ, Melanson EL, Stevens-Lapsley JE, Christiansen CL. Physical activity after total knee arthroplasty: A critical review. World J Orthop . 2015; 6: 614–22. 39. de Groot IB, Bussmann HJ, Stam HJ, Verhaar JA. Small increase of actual physical activity 6 months after total hip or knee arthroplasty. Clin Orthop Relat Res. 2008 Sep;466(9):2201-8. 40. Vissers MM, Bussmann JB, de Groot IB, Verhaar JA, Reijman M. Physical functioning four years after total hip and knee arthroplasty.Gait Posture. 2013 Jun;38(2):310-5. 41. Van Onsem S, Verstraete M, Dhont S, Zwaenepoel B, Van Der Straeten C, Victor J. Improved walking distance and range of motion predict patient satisfaction after TKA. Knee Surgery, Sport Traumatol Arthrosc . 2018; 26: 3272–9.

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42. Williams DP, O’Brien S, Doran E, et al. Early postoperative predictors of satisfaction following total knee arthroplasty. Knee . 2013; 20: 442–6. 43. Huijben B, van Schooten KS, van Dieën JH, Pijnappels M. The effect of walking speed on quality of gait in older adults. Gait Posture . 2018; 65: 112–6. 6 44. Hortobágyi T, Lesinski M, Gäbler M, VanSwearingen JM, Malatesta D, Granacher U. Effects of Three Types of Exercise Interventions on Healthy Old Adults’ Gait Speed: A Systematic Review and Meta-Analysis. Sport Med . 2015; 45: 1627–43. 45. Alice B-M, Stéphane A, Yoshisama SJ, et al. Evolution of knee kinematics three months after total knee replacement. Gait Posture . 2015; 41: 624–9. 46. Hardt S, Schulz MRG, Pfitzner T, et al. Improved early outcome after TKA through an app-based active muscle training programme—a randomized-controlled trial. Knee Surgery, Sport Traumatol Arthrosc . 2018; 26: 3429–37.

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SUPPLEMENTARY MATERIAL Supplementary table 1. Questionnaire gait behavior, and daily life gait quality measures Perceived ability mGES (0-100) PROMs OKS (0-48) HAAS (0-18) VAS pain rest (0-10) VAS pain movement (0-10) KOOS-PS (100-0) VAS QoL (0-100) EQ5D (0-1) Gait behavior Quantity (Number of 8 second epochs per day) Gait speed (meters/second) Gait quality Stride time (seconds) Stride time variability (seconds) Stride Regularity VT Stride Regularity ML Stride Regularity AP Sample Entropy VT Sample Entropy ML Sample Entropy AP Gait Symmetry (Harmonic Ratio) VT Gait Symmetry (Harmonic Ratio) ML Gait Symmetry (Harmonic Ratio) AP Local Divergence Exponent Wolf VT (s-1) Local Divergence Exponent Wolf ML (s-1) Local Divergence Exponent Wolf AP (s-1) Local Divergence Exponent Rosenstein VT (s-1) Local Divergence Exponent Rosenstein ML (s-1) Local Divergence Exponent Rosenstein AP (s-1) Low Frequency percentage VT < 0.7 Hz Low Frequency percentage ML < 10 Hz Low Frequency percentage AP < 0.7 Hz Gait Smoothness (Index of Harmonicity) VT Gait Smoothness (Index of Harmonicity) ML Gait Smoothness (Index of Harmonicity) AP Dominant Frequency’s Amplitude VT Dominant Frequency’s Amplitude ML Dominant Frequency’s Amplitude AP

Baseline

3 months follow-up

p-value

67 (24)

79 (25)

.001

29 (9.5) 6 (4) 4.5 (4) 7 (2) 43 (12.2) 70 (15) 0.78 (0.13)

38.5 (8.3) 7 (5) 1 (3) 3 (3) 29.7 (13.7) 78 (19) 0.84 (0.2)

<.001 .009 <.001 <.001 <.001 .012 .001

218.86 (178.50) 0.85 (0.03)

222.71 (122.76) 0.79 (0.13)

.421 .126

1.24 (0.09) 0.06 (0.03) 0.52 (0.14) 0.42 (0.10) 0.44 (0.10) 0.23 (0.06) 0.30 (0.07) 0.26 (0.06) 1.45 (0.27) 1.34 (0.16) 1.27 (0.21) 1.60 (0.25) 1.74 (0.24) 1.70 (0.20) 0.78 (0.14) 0.66 (0.09) 0.67 (0.11) 0.22 (0.13) 89.80 (7.57) 3.37 (2.79) 0.47 (0.21) 0.30 (0.14) 0.56 (0.11) 0.45 (0.14) 0.31 (0.12) 0.43 (0.11)

1.26 (0.10) 0.06 (0.03) 0.50 (0.12) 0.44 (0.12) 0.47 (0.10) 0.23 (0.08) 0.31 (0.05) 0.26 (0.06) 1.40 (0.26) 1.34 (0.24) 1.25 (0.18) 1.65 (0.22) 1.70 (0.25) 1.64 (0.23) 0.79 (0.15) 0.66 (0.14) 0.65 (0.09) 0.24 (0.14) 91.14 (5.59) 3.60 (2.12) 0.40 (0.21) 0.31 (0.16) 0.61 (0.17) 0.39 (0.15) 0.34 (0.13) 0.46 (0.13)

.001 .350 .868 .073 .037 .091 .936 .856 .137 .446 .607 .658 .086 .086 .226 .845 .081 .455 .032 .500 .020 .149 .036 .005 .060 .035

Data in Median (IQR); VT=vertical; ML=medial-lateral; AP=anterior-posterior; GES=Gait Efficacy Scale; HAAS=High Activity Arthroplasty Score; VAS=Visual Analogue Scale; KOOS=Knee Osteoarthritis Outcome Scale; QoL=Quality of Life; OKS=Oxford Knee Score

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171

CONCLUDING REMARKS

CHAPTER 8 Epilogue

CH APTE R 8

THESIS SUMMARY The aim of this thesis was to assess several innovations aimed at improving functional outcome and functional outcome measures in total knee arthroplasty (TKA). In Part 1, the effects of a fast-track protocol and of changes in bearing design of the prosthesis were evaluated for their effect on functional outcome in TKA patients by performing prospective randomised trials and a comprehensive literature review. In Part 2, a questionnaire designed for more active patients was validated in Dutch, and instrumented gait analyses using trunk-based accelerometry in both clinical and domestic settings were studied for their possible added value in evaluating functional outcome of TKA patients.

PART 1 Improving functional outcome Fast-track The introduction in hospitals of fast-track protocols for TKA patients has led to quicker mobilisation and discharge from hospital, whilst reducing pain and use of analgesics and without an increase in complications or readmissions. While patients staying in hospital for less than a week after their operation would be the exception rather than the rule up to the 1990s, fast-track protocols reduced length of stay (LOS) to as short as three to five days in the first decade of this millennium. After this, several new protocols were developed to further reduce LOS and help patients rehabilitate more quickly. Studies evaluating these protocols most often focused on clinical outcome on the medium- to long-term follow-up, with patients having their first follow-up measurements done two to six weeks after the surgery. This feels contradictory to the measures often incorporated in fast-track protocols, which are aimed at reducing pain and facilitating start of rehabilitation in the first hours and days after surgery. Therefore, in Chapter 2, we used a randomised clinical trial (RCT) to assess our own fast-track protocol aimed at discharge two days after TKA surgery, with a special emphasis on the first seven days. We included both clinical and functional outcome parameters. Fifty patients were randomly allocated to two groups, and followed up to five years after their operation. Patients with the fast-track protocol had significantly lower VAS scores for pain directly after and in the first and second hour after the surgery compared to the regular protocol. VAS scores for knee pain at rest were significantly lower in this group throughout the first week. Significantly better scores were also seen on several functional tests in the first week in the fast-track protocol group, but

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only a few significant differences were found at 2, 6, 12 weeks and 1, 2, and 5 years after surgery. This indicates that discharge from hospital two days after TKA is achievable in most patients, and that the most important gains of a fast-track protocol are achieved in the first seven days without adverse effects on the long term. Research into fast-track protocols should therefore focus more on this early time period. Implant design Several proposed limitations of fixed bearing TKA (FB-TKA) in replicating three dimensional natural knee motion led to the development of mobile bearing TKA (MB-TKA) in the 1980s. Because of the mobility of the poly-ethylene (PE) insert, MB-TKA was hypothesized to have several important advantages over FB-TKA: less wear of the PE insert, less signs of loosening of the prosthesis, a higher survival rate of the prosthesis, and improved clinical outcome. A large number of studies comparing MB-TKA and FB-TKA have been performed, analysing different factors of both types of prostheses. Reviews and meta-analyses on this subject have so far been unable to determine differences between the bearing types. However, these reviews and meta-analyses often used the same limited number of randomised controlled trials. These types of reviews omit important studies with a lower level of evidence, even though these could possibly provide added insight as to which type of bearing would be preferential. We therefore decided to perform a comprehensive literature review of all relevant studies comparing MB-TKA and FB-TKA, as reported in Chapter 3. After including and analysing 127 articles (9 meta-analyses, 3 systematic reviews, 48 RCTâ&#x20AC;&#x2122;s, 44 comparative studies, 10 reviews and 13 studies that examined patients who received bilateral TKA (one MB-TKA and one FB-TKA)), we concluded that there were still only a few articles that reported only minor differences between the two types of bearing. Preference for any bearing type should therefore be decided on other factors, e.g. surgeonsâ&#x20AC;&#x2122; experience with certain implants. There have been developments in the design of PE inserts of both MB-TKA and FB-TKA prostheses over the last years, with manufacturers and researchers hoping that these new designs would improve outcome in patients. In Chapter 4, we examined four different types of inserts, two mobile bearing (rotating and rotating/ translating) and two fixed bearing (normal dish and deep dish). The study included analysis of survival, quality of life (QoL), clinical, and functional outcome parameters. Out of 237 patients included in two different hospitals, 146 completed the whole five-year protocol. No differences were found when looking at functional and QoL parameters. A small significant difference between the two types of

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mobile bearing inserts over time was found in Knee Society Scores, which was thought to have no clinical relevance. Survival of MB-TKA was worse compared to FB-TKA (94.7% and 99.2% respectively) after five years. Time to revision for any reason was in favour of FB-TKA. This difference was not found when looking at the specific inserts within groups, although there were indications that the mobile bearing rotating/translating insert performed the least well out of the four inserts studied. We concluded that when using this specific type of TKA prosthesis, choosing FB-TKA over MB-TKA would be advisable. Â

PART 2 Improving functional outcome measures Patient Reported Outcome Measures The most commonly used way of assessing clinical outcome of TKA is by asking patients to complete questionnaires, known as patient reported outcome measures (PROMs). This is an easy method to gather data on patient satisfaction, experienced pain, and QoL. Most of these questionnaires have been used for several decades. However, recent analyses of the clinimetric properties of PROMs showed that there are often ceiling effects when assessing TKA patients. This could be partly due to the recent developments in TKA patient populations, with patients being younger when undergoing TKA and remaining active up to an older age. To allow researchers to discriminate between active and very active patients, the High Activity Arthroplasty Score (HAAS) was developed by Talbot et al., and has already been validated in both English and French. Chapter 5 contains our cross-cultural translation and validation of the HAAS into Dutch. One hundred and eight patients (51 after total hip artroplasty and 57 after TKA) completed the HAAS and several other PROMs. The Dutch version of the HAAS showed a good internal consistency and had significant positive correlations with almost all other PROMs that were used. Importantly, the HAAS did not show a floor or ceiling effect. Gait analysis Accelerometers and other inertial measurement units (IMUs) have been successfully used for years in the field of human movement sciences for the analysis of movement tasks, most notably gait, and the effects of several diseases on gait. Currently, these devices are increasingly used in the field of orthopaedic surgery. This is mainly due to the decreased size and improved availability of accelerometers. To determine whether accelerometers could be used in the

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analysis of TKA patients, we used trunk-based accelerometers to analyse the quality of 65 patients’ gait before and one year after unilateral TKA in Chapter 6. These accelerometers measure acceleration in three dimensions: anterior-posterior (AP), mediolateral (ML), and vertical (VT). Gait measurements consisted of patients walking 50 meters twice during their outpatient clinic visit. Patients were also asked to complete several PROMs together with the gait measurements. A principal axis factor analysis was done on the gait quality parameters, to determine which parameters were most representative for gait quality. Three gait quality factors were identified: ‘AP/VT gait quality’, with stride regularity-VT as the highest loading parameter with a loading of -0.883; ‘ML gait quality’, with stride regularity-ML with a factor loading of 0.784; and ‘Symmetry’, with harmonic ratioAP as parameter with a loading value of 0.787. All PROMs were grouped in a separate factor from the gait quality parameters, implying that instrumented gait quality parameters measure different aspects of functional outcome than PROMs. Correlations between the values of the gait parameters of each factor and the highest loading parameter in the PROMs factor (the Oxford Knee Score (OKS)) between both time points were calculated, which showed only weak to moderate associations. This confirmed the notion that PROMs and instrumented gait quality measurements evaluate different aspects of functional outcome after TKA, and that therefore accelerometer measurements could be of added value in the functional evaluation of TKA patients. To expand on the knowledge gathered in Chapter 6, we wanted to see which results accelerometer analysis of TKA patients would yield when performed in the domestic setting rather than in the clinical setting of the outpatient clinic. Therefore, in Chapter 7, 38 patients wore an accelerometer for a whole week both before and three months after their knee was replaced. Again, patients were asked to also complete PROMs at the same time as their gait analysis. At both time points, data were collected on gait quality, gait behavior (in the form of both quantity of gait and walking speed), and on patients’ perception of their own walking abilities. Using the same parameters that had the highest loading for the gait quality factors in the previous chapter, no significant improvement in either gait quality parameters or gait behavior after three months were found. Additionally, no significant improvement was seen in dynamic reliability and stability gait quality parameters. In contrast to this, both patients’ perceived walking abilities and their PROMs scores did improve significantly. This discrepancy shows that patients’ own perception of their walking abilities does not necessarily represent their actual daily function and activities. To measure what level of functional outcome patients are achieving at home, it appears accelerometers

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are needed besides PROMs. Measuring functional outcome after TKA with accelerometers in a daily life setting could therefore provide supplementary information for orthopaedic surgeons and other caretakers, and could possibly be used for improving rehabilitation strategies for patients on an individual level.

GENERAL DISCUSSION PART 1 Improving functional outcome The challenges in reporting outcome of total knee arthroplasty In this thesis, I used several different approaches to improve functional outcome and measurement of functional outcome of undergoing total knee arthroplasty (TKA). Assessment of outcome after TKA is challenging and includes different aspects like satisfaction, pain relief, and function. Unfortunately, in literature the definition and use of these terms varies significantly. Especially the term â&#x20AC;&#x153;functionâ&#x20AC;? has been used to describe everything from scores on function-related questionnaires, easy tasks as being able to stand up or perform walking tasks (e.g. the Timed Up & Go test), the range of motion (ROM) of flexion and extension of the knee, to sophisticated analyses of gait patterns using complex instrumentation and algorithms. Another complicating factor in trying to improve functional outcome and functional outcome measures after TKA is that a large number of different factors are directly or indirectly associated with outcome. The preoperative expectations of patients, pain relief, and improvement in knee ROM are the factors most often reported in literature as being associated with TKA outcome.1 However, these factors often influence each other as well. We know for example that more intense pain during flexion and extension before surgery is predictive of higher pain scores after surgery.2 Also, Jain et al. found that attention for increasing preoperative patient expectations can improve scores on patient related outcome measures (PROMs), but does not increase postoperative satisfaction rates.3 These findings show that when researching functional outcome after TKA attention should be given to both preoperative and postoperative measurements since both time points could provide opportunities for improvement. Another factor associated with functional outcome after TKA is patient satisfaction. Dissatisfaction after TKA has proven to be an especially persistent and multifactorial problem, which is influenced by other factors besides function as varying as the nation in which people live4, to the kindness of hospital staff and the quality of hospital food.5 Improving functional outcome after TKA

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by increasing knee ROM and the distance that patients are able to walk and the ease and confidence with which they can do so can have positive effects on patient satisfaction rates.6 Studies focusing on addressing the issue of patient satisfaction after TKA should therefore include functional outcome, preferably with both objective and subjective measurements, as part of their analysis. The race to the fastest discharge In chapter 2, we assessed a fast-track protocol for TKA patients. The goal of this study, which was started in 2011, was to determine whether a discharge after 2 days was feasible compared to the then average length of stay (LOS) of 4-5 days after TKA. The results showed that this was indeed feasible with the most noted improvements (lower pain scores and improved functional outcome as measured with the Timed Up & Go test and several simple tasks) in the fast-track group in the first hours and days after surgery. When the study was finished, an average discharge after 2-3 days had already become the norm in daily orthopaedic practice. This was supported by a retrospective study by Sutton et al. in 2016, who found that in a group of over 30.000 TKA patients, a discharge within two days was safe and even seemed to decrease complications in certain patient groups.7 Determining who are the right patients for fast-track TKA can be a challenge, with related factors including age, gender, comorbidities, type of anesthesia, and even on which day of the week patients are operated.8,9 In the last couple of years, the boundaries of decreasing LOS have been researched even further, with the aims of researchers being set on discharging patients on the day of surgery: outpatient TKA. In 2015, several researchers with established track-records on fast-track TKA published an article in which they noted several limitations on the concept of outpatient TKA.10 However, recently there has been a noted increase in the number of studies into outpatient TKA. In small groups of TKA patients (especially relatively young and healthy patients), outpatient TKA appears to be possible without noted increases in resubmissions, reoperations, and complications.11–13 The effect of same-day discharge after TKA on functional outcome has not yet been extensively studied. One study by Schotanus and coworkers found similar physical activity levels six weeks after surgery as measured with accelerometers in a small group of outpatient TKA patients compared to patients in a fast-track protocol.14 At this point in time, outpatient TKA has some promising aspects, but accurate patient selection is critical. This means that outpatient TKA has a way to go before being feasible for a majority of patients. Awaiting further studies on functional outcome of outpatient TKA, a hospital stay of one to two days after TKA appears to be the preferred LOS for most TKA patients with the most optimal functional recovery.

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Developments in prosthesis design aimed at improving functional outcome As demonstrated in chapter 3, numerous articles have been published on the (supposed) benefits of either mobile bearing TKA (MB-TKA) or fixed bearing TKA (FB-TKA). We concluded that, from the literature on several aspects of outcome after TKA, up to that point no preference for one type of design over another could be given. This conclusion was also made in the Cochrane review on this subject.15 This conclusion is, however, not shared by everyone. A study by Vertullo et al. used retrospective data from an arthroplasty register, and reported that the combination of a minimally stabilized, fixed bearing TKA with cross-linked polyethylene with patella resurfacing reduced the revision risk compared to other combinations.16 It is, however, doubtful that this conclusion can be maintained for all different types of TKA prosthesis. In our review, the only functional outcome that was examined in the included papers (if reported) was ROM in flexion and extension of the knee. Out of the 39 studies with level I evidence that reported data on ROM, only one found a significant difference, in this case in favor of MB-TKA. There have only been a few studies that have compared MB-TKA and FB-TKA, and have included functional outcome measurements beyond flexion and/or extension ROM of the affected knee. One study found no difference between MB-TKA and FB-TKA in patellofemoral pain in simple functional tests such as chair rise and stair climb.17 To our knowledge, only two studies have included more extensive functional outcome comparisons between MB-TKA and FB-TKA. Urwin et al. reported no significant differences in spatiotemporal, kinematic, and kinetic parameters during walking, but this was in a very small group of 8 MB-TKA patients and 8 FB-TKA patients.18 Jolles et al. divided 26 MB-TKA patients and 29 FB-TKA patients in subgroups by age, and found better improvement in gait analysis (speed, knee angles, accelerometer measurements) for FB-TKA in patients over 70 years of age, and for MB-TKA in patients under 70 years old.19 This was one of the reasons that we included goniometry during walking and temporal gait parameters in the randomised controlled trial comparing two types of MBTKA and two types of FB-TKA reported in chapter 4. No differences in maximum flexion during the swing and stance phase of walking or in single leg support times were found between the bearing types. This was in a much larger group of 123 FB-TKA patients and 114 MB-TKA patients. When combining the results of chapters 3 and 4, it can be argued that there is no longer a place for studies comparing clinical outcomes of MB-TKA and FB-TKA for multiple brands trying to form a general conclusion. Only studies with longterm follow-up for one specific brand of prosthesis, similar to what was done in chapter 4, could possibly be expected to have clinical consequences. More

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research is needed to form similar conclusions for possible differences in functional outcome between MB-TKA and FB-TKA. However, when taking the results of chapter 4 into account, it is likely that additional studies will probably not find clinically significant differences in functional outcomes between the two types of bearing. Together with MB-TKA, there have been several other developments in TKA prosthesis design that aim to improve functional outcome by replicating anatomical knee function in patients.20 Reduction of anatomical axial rotation occurs in all types of TKA design (MB/FB-TKA, cruciate retaining etc.)21, and is therefore thought to be the best target for improving functional outcome via prosthesis design. One of these innovations is the bicruciate-retaining TKA, where the tibial component is designed in such a way that both the anterior and posterior cruciate ligaments can be spared. Unfortunately, even though retaining both cruciate ligaments appears to allow for a more anatomical femoral rollback, the need for a relatively flat polyethylene insert in this type of prosthesis appears to prevent a significant improvement in axial rotation in vitro22. In vivo, only flexion and extension ROM has been reported as functional outcome of bicruciateretaining TKA, which has been satisfactory.23 Similarly, no satisfactory improvement in function measured with ROM have been found in gender-specific designs, which offer a â&#x20AC;&#x153;narrowâ&#x20AC;? option of the femoral component theorized to be more suited for the female femoral anatomy.24 Since prosthesis design does appear to influence functional outcome after TKA25 it remains a potential target for gains in functional outcome, even though many of the recent design optimizations have provided no or only small improvements.

PART 2 Improving functional outcome measures PROMs in evaluation of functional outcome of TKA PROMs are the most widely used tool for assessing outcome in healthcare, and this is especially the case for orthopaedic surgery. Different PROMs are available to quantify pain relief, satisfaction, mental health, quality of life (QoL), function, and many other aspects of health-related outcome. The advantages of PROMs are plenty: they are easy to administer to patients, require little time to complete and provide a possibility for hospitals, insurance companies and governmental institutions to compare outcome and results of different healthcare professionals. For example, in the Dutch national arthroplasty register (Landelijke Registratie Orthopedische Implantaten, LROI) PROM scores are collected for each TKA

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patient before and at 6 and 12 months after surgery, which allows orthopaedic departments to compare their own outcomes to the national average. In this thesis also, PROMs were used or reported in every chapter. With increasing use of PROMs in TKA research and increasing understanding of their properties, several limitations to the use of PROMs have been discovered. Firstly, evidence on the clinimetric properties of most PROMs is missing, or it is unclear whether the properties are adequate. Clinimetric properties are the validity, reliability, and responsiveness of the instrument.26 A large systematic review by Gagnier et al. in 2017 found that for only three out of 32 often used PROMs in TKA enough evidence was available to state that their different clinimetric properties were sufficient.27 A similar result was found by Ramkumar et al. in 2015, who only found adequate evidence for sufficient validity and reliability for four different PROMs.28 This does, however, not mean that the other PROMs do not have adequate clinimetric properties, but that these properties need to be assessed. Secondly, research has shown that numerous external factors influence PROMs scores. Amongst many others, age29, body mass index30, back pain31, bad PROMs scores for the contralateral knee32, preoperative pain and mental health PROMs scores33, preoperative opioid use34, and increasing comorbidity after surgery35 have all been associated with lower or higher PROMs scores in TKA patients. When looking for example at age, patients below 60 years old are more likely to have lower scores on PROMs after TKA surgery.29 This could be due to the higher demands these patients place on their knee, since patients in this age category would more often still expect to be able to work or participate in sports. In addition, more active patients regularly attain the highest scores for activity-related PROMS, which means that researchers are unable to distinguish active and very active patients (ceiling effect). For this reason the High Activity Arthroplasty Score (HAAS), that was translated and validated into Dutch in Chapter 5, was developed. In our study, 51 THA and 57 TKA patients were evaluated. There were no ceiling or floor effects in their HAAS scores, but ceiling effects were found in the QoL, pain and clinical outcome PROMs that were also evaluated. This indicates that the HAAS could help differentiate between patients with good or very good outcome after TKA and THA. The ability of PROMs to fully quantify functional outcome after TKA has been questioned several times.36 Self-reported questionnaires show strong correlations with pain experienced by patients, which implies that questionnaires that have function items included in their (sub)scores might actually still be assessing pain instead of function.37 In this thesis, there were also several results that imply that PROMs do not provide a complete picture of functional outcome after TKA. In

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chapter 6, both gait parameters and PROMs showed significant improvements 1 year after TKA, but a principal factor analysis resulted in a separate factor for all PROMs scores that were evaluated. This was a clear result showing that subjective measurements with the PROMs quantify different aspects of functional outcome than objective instrumented gait parameters. This is line with other studies comparing accelerometry and PROMs in arthroplasty patients.38 In chapter 7, another example of the limitations of PROMs in assessing functional outcome was demonstrated. Contrary to the results of chapter 6, this time PROMs scores had improved significantly three months after surgery, but both gait quality and gait behavior had not. This is an interesting finding, because this shows that patientsâ&#x20AC;&#x2122; subjective opinion on the function of their affected knee has improved, even though quantifying this with instrumented gait analysis did not confirm their perceived improvements. Again, this is in line with earlier results. Naili et al. found a similar discrepancy between increased PROMs scores and persisting kinetic gait deviations using a video motion analysis system in 28 patients one year after TKA.39 Based on these results one could argue that PROMs alone are not enough to supply a thorough and complete overview of functional outcome after TKA, as they do represent patientsâ&#x20AC;&#x2122; gait quality, quantity, and/or walking speed. As understanding functional outcome after TKA is becoming increasingly relevant with a younger and more active patient population, researchers and surgeons should be aware of these limitations and try to provide additional methods of analysis whenever possible when using PROMs in the evaluation of functional outcome of TKA patients. This could allow them to more accurately identify which patients might benefit from increased focus on functional rehabilitation, or in the future maybe assist in determining which patients are more at risk for impaired function after TKA even before the procedure is performed. Accelerometry in evaluation of functional outcome of TKA In chapters 6 and 7 of this thesis, we used accelerometers to analyse gait before and after TKA. The trunk-based accelerometers used in our studies allowed us to assess gait quality using symmetry, stability and variability measures as well as spatio-temporal gait parameters. Trunk-based accelerometer gait quality analysis was validated before in several other fields of research, including stroke rehabilitation40 and fall prediction in the older adults.41 Â We assessed TKA patients with accelerometers both in a clinical (chapter 6) and in a domestic setting (chapter 7). As mentioned above, in the clinical setting, gait quality parameters showed significant improvements after one year, but in the domestic setting after three months there was no significant improvement. This

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could be due to the timing of the follow-up measurements, but this is most likely at least in part due to the difference in quality of gait of patients between a clinical and daily-life setting. Several studies have demonstrated that values of gait quality parameters are on average worse in daily-life compared to a controlled clinical research environment.42,43 This is understandable, as patients can be expected to perform better at walking tasks when concentrating in a laboratory setting, with researchers monitoring their movements. It is therefore unfortunate that patients do not achieve the same level of gait quality at home. The results of chapter 7 show that even though patients report that they have more faith in their walking abilities during daily activities after TKA, both their measured gait quality and gait behavior do not support this perceived increase in abilities. The fact that patients’ gait behavior, as measured in both gait speed and gait quantity, did not show improvement after surgery implies this could be a target for increasing the outcome of postoperative rehabilitation. If gait patterns normalize, patients are more likely to report that their knee feels “normal”.44 This is especially true for gait speed, where patients that are able to achieve higher walking speeds after surgery are more likely to be satisfied with their TKA.6 That gait speed is an area of concern in TKA patients has already been demonstrated, since TKA patients walk slower when compared to healthy controls or unicompartmental knee arthroplasty (UKA) patients.45 By identifying which gait quality, speed and quantity parameters remain below optimal after TKA, it should be possible to adjust postoperative exercise and rehabilitation protocols in such a way that these issues can be addressed in the future. External factors might also influence the results of instrumented gait analysis, as demonstrated recently by a McClelland et al. who found that knee kinematics in female patients might be worse than those of their male counterparts when using a mixed-sex cohort.46 Other patient characteristics that might influence gait quality and quantity could be identified in future research, and these should be taken into account when forming conclusions based on accelerometer data in TKA patients. To increase the likelihood of surgeons applying accelerometry in their daily practice, more research into influencing factors and the differences between measurements in a clinical and in a daily-life setting is warranted. Both for patients’ functional capacity and abilities after TKA as measured in a clinical setting, as well as for patients’ actual gait performance (both quality and quantity) once they are back in their own home, the results of this thesis and of earlier studies show that instrumented gait analysis is needed to form a complete picture of functional outcome of patients undergoing TKA surgery.

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FUTURE PERSPECTIVES Based on the results of the studies included in this thesis, several questions for future research can be formulated. PART 1 Improving functional outcome As mentioned above, outpatient TKA has become the new trend in orthopaedic research trying to expand on the success of fast-track protocols. For most TKA studies and especially with outpatient TKA, the reduced hospital phase in TKA rehabilitation means that a larger role for rehabilitation centers and physiotherapists is needed. Objective gait measurements could give therapists an extra tool with which they can monitor their patients to improve their rehabilitation. Future studies into outpatient TKA should therefore ideally include both a method for instrumented gait analysis, as well as extensive descriptions and analysis of rehabilitation protocols. Including gait parameters in research comparing functional outcome of FB-TKA and MB-TKA has also only been sparingly performed. However, since so many studies into this topic have yielded no clear advise for surgeons on whether one type of bearing should be preferred over another, resources of researchers could better be used to study the effects of different aspects of implant design on functional outcome. As UKA (both medial and lateral) and patellofemoral prostheses are being used more often as treatment of unicompartmental OA of the knee, more studies comparing functional outcome of UKA and TKA will likely be performed in the future. When taking into account the results of chapters 2, 6 and 7 of this thesis, to provide a complete evaluation of functional outcome, these studies should incorporate measurements of both PROMs and gait parameters, with follow-up measurements performed on shortterm as well as long-term. Furthermore, as functional recovery appears to take longer after surgery then was so far expected, including preoperative and postoperative rehabilitation in TKA surgery could possibly provide insights in ways to shorten the time it takes for patients to reach satisfactory levels of daily function. PART 2 Improving functional outcome measures Several aspects of the use of accelerometers for analyzing functional outcome after TKA remain to be studied, before widespread application together with PROMs can be expected. Further innovations in size, battery life, and wearability of accelerometers could be expected to improve patientsâ&#x20AC;&#x2122; willingness to wear these devices, and hopefully address the dropout rate found in chapter 7 and in other studies using accelerometers.47 When understanding improves of which gait

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quality parameters are associated with patientsâ&#x20AC;&#x2122; functional outcome after TKA surgery, it is possible to use this information in determining which patients are more likely to perform worse in terms of function based on their preoperative gait characteristics like walking speed, loss of muscle strength, and/or gait quality. This has already been tried for spatiotemporal gait parameters in a study by Kluge et al., who looked at spatiotemporal gait variables using a foot worn accelerometer for 4 bouts of 10 meters walking, and found that preoperative values of stride time and stride length might be predictive of better or worse improvement in PROMs scores after TKA. This was done in a small group of 24 patients, of whom 25% declined to participate for follow-up measurements.47 This was only one study, and further expanding knowledge on this subject would allow us to advise patients beforehand and improve their postoperative functional outcome by addressing gait abnormalities before surgery, during hospital stay, and afterwards during rehabilitation at home. Considering the differences in gait quality results between the clinical measurements of chapter 6 and the daily-life measurements of chapter 7, it would be interesting to obtain repeated measurements in both settings, before and after TKA surgery for a single cohort of TKA patients. This could provide insight into which gait quality, speed and quantity parameters remain lacking in daily-life, or which patient categories need extra guidance or training in improving their walking abilities. Ideally, in the future these data would be collected using modern devices like a patientâ&#x20AC;&#x2122;s own smartphone or smart watch, and an algorithm could be constructed that would combine patient characteristics, PROMs data and accelerometer data into one comprehensive score or value. Since modern smartphones already contain accelerometers, this should theoretically be possible. Smartphone apps are already used with success in muscle training after TKA.48 When accelerometers are combined with an app where patients can complete their PROMs questionnaires and a cloud-based system that allows researchers and physicians to monitor their patientsâ&#x20AC;&#x2122; data, this could also be used to detect patients that are performing below average. These patients can then be actively approached to improve their rehabilitation and outcome. To develop such a system, a multidisciplinary approach with orthopaedic surgeons, human movement scientists, physiotherapists, data scientists, and software developers is needed.

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CONCLUSIONS In this thesis, I aimed to assess aspects of several innovations that pursue improvements in functional outcome and functional outcome measures in TKA. The insights obtained in Part 1 show that when trying to improve functional outcome using fast-track protocols, special consideration should be given to the first hours and days after the surgery as the most marked improvement is found in the first week. When comparing FB-TKA and MB-TKA almost all literature, including the studies reported in this thesis, report no differences in clinical and functional outcome. Overall, the added value of more research into bearing types of TKA seems questionable. This work supports the need for improved methods of measuring functional outcome with several possible methods presented in Part 2. Better understanding of which patients function on a high or very high level can be obtained with the HAAS, a recently developed PROM now translated into Dutch. The results in this thesis show that using accelerometers to evaluate quality of gait in TKA patients can be used to compliment PROMs scores, as they measure different aspects of functional outcome. Finally, patientsâ&#x20AC;&#x2122; own perceptions on their walking abilities in daily life do not appear to correspond with their measured actual abilities and achievements in gait quality, speed, and quantity, meaning more focus is needed during postoperative rehabilitation on improving functional behavior and gait in daily-life activities. Further evaluation of the use of accelerometers in the evaluation of functional outcome after TKA could help to obtain a better understanding of different aspects of gait and functional outcome, and thereby provide surgeons, researchers, and other caretakers with the means to optimise the functional rehabilitation of TKA patients before and after surgery.

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18. Urwin SG, Kader DF, Caplan N, St Clair Gibson A, Stewart S. Gait analysis of fixed bearing and mobile bearing total knee prostheses during walking: Do mobile bearings offer functional advantages? Knee. 2014 Mar;21:391–5. 19. Jolles BM, Grzesiak A, Eudier A, Dejnabadi H, Voracek C, Pichonnaz C, et al. A randomised controlled clinical trial and gait analysis of fixed- and mobile-bearing total knee replacements with a five-year follow-up. J Bone Joint Surg Br. 2012 May;94-B:648–55. 20. Shi X, Shen B, Yang J, Kang P, Zhou Z, Pei F. In vivo kinematics comparison of fixed- and mobilebearing total knee arthroplasty during deep knee bending motion. Knee Surgery, Sport Traumatol Arthrosc. 2014 Jul 12;22:1612–8. 21. Dennis DA, Komistek RD, Mahfouz MR, Walker SA, Tucker A. A multicenter analysis of axial femorotibial rotation after total knee arthroplasty. Clin Orthop Relat Res. 2004 Nov;180–9. 22. Heyse TJ, Slane J, Peersman G, Dirckx M, van de Vyver A, Dworschak P, et al. Kinematics of a bicruciate-retaining total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2017 Jun 11;25:1784–91. 23. Pritchett JW. Bicruciate-retaining Total Knee Replacement Provides Satisfactory Function and Implant Survivorship at 23 Years. Clin Orthop Relat Res. 2015 Jul 27;473:2327–33. 24. Cheng T, Zhu C, Wang J, Cheng M, Peng X, Wang Q, et al. No clinical benefit of gender-specific total knee arthroplasty. Acta Orthop. 2014 Aug 23;85:415–21. 25. Hamilton DF, Burnett R, Patton JT, Howie CR, Moran M, Simpson AHRW, et al. Implant design influences patient outcome after total knee arthroplasty: a prospective double-blind randomised controlled trial. Bone Joint J. 2015 Jan;97-B:64–70. 26. Vet HCW de, Terwee CB, Mokkink LB, Knol DL. Measurement in medicine : a practical guide. 2011. Cambridge University Press. 1st edition. 27. Gagnier JJ, Mullins M, Huang H, Marinac-Dabic D, Ghambaryan A, Eloff B, et al. A Systematic Review of Measurement Properties of Patient-Reported Outcome Measures Used in Patients Undergoing Total Knee Arthroplasty. J Arthroplasty. 2017 May;32:1688-1697.e7. 28. Ramkumar PN, Harris JD, Noble PC. Patient-reported outcome measures after total knee arthroplasty: a systematic review. Bone Joint Res. 2015 Jul;4:120–7. 29. Townsend L, Roubion R, Bourgeois D, Leonardi C, Fox R, Dasa V, et al. Impact of Age on PatientReported Outcome Measures in Total Knee Arthroplasty. J Knee Surg. 2018 Jul 25;31:580–4. 30. Giesinger JM, Loth FL, MacDonald DJ, Giesinger K, Patton JT, Simpson AHRW, et al. Patientreported outcome metrics following total knee arthroplasty are influenced differently by patients’ body mass index. Knee Surg Sports Traumatol Arthrosc. 2018 Nov 7;26:3257–64. 31. Schroer WC, Diesfeld PJ, LeMarr AR, Morton DJ, Reedy ME. Functional Outcomes After Total Knee Arthroplasty Correlate With Spine Disability. J Arthroplasty. 2016 Sep;31:106–9. 32. Kahn TL, Soheili AC, Schwarzkopf R. Poor WOMAC scores in contralateral knee negatively impact TKA outcomes: data from the osteoarthritis initiative. J Arthroplasty. 2014 Aug;29:1580–5. 33. Berliner JL, Brodke DJ, Chan V, SooHoo NF, Bozic KJ. Can Preoperative Patient-reported Outcome Measures Be Used to Predict Meaningful Improvement in Function After TKA? Clin Orthop Relat Res. 2017 Jan 8;475:149–57. 34. Smith SR, Bido J, Collins JE, Yang H, Katz JN, Losina E. Impact of Preoperative Opioid Use on Total Knee Arthroplasty Outcomes. J Bone Jt Surg. 2017 May;99:803–8. 35. Hilton ME, Gioe T, Noorbaloochi S, Singh JA. Increasing comorbidity is associated with worsening physical function and pain after primary total knee arthroplasty. BMC Musculoskelet Disord. 2016 Dec 7;17:421. 36. Luna IE, Kehlet H, Peterson B, Wede HR, Hoevsgaard SJ, Aasvang EK. Early patient-reported outcomes versus objective function after total hip and knee arthroplasty: a prospective cohort study. Bone Joint J. 2017 Sep;99-B:1167–75. 37. van Dijk GM, Veenhof C, Lankhorst GJ, Dekker J. Limitations in activities in patients with osteoarthritis of the hip or knee: the relationship with body functions, comorbidity and cognitive functioning. Disabil Rehabil. 2009 Jan 15;31:1685–91. 38. Bolink SAAN, Grimm B, Heyligers IC. Patient-reported outcome measures versus inertial performance-based outcome measures: A prospective study in patients undergoing primary total knee arthroplasty. Knee. 2015 Dec;22:618–23.

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39. Naili JE, Iversen MD, Esbjörnsson A-C, Hedström M, Schwartz MH, Häger CK, et al. Deficits in functional performance and gait one year after total knee arthroplasty despite improved selfreported function. Knee Surg Sports Traumatol Arthrosc. 2017 Nov;25:3378–86. 40. Punt M, Bruijn S, Wittink H, Port I, DieÃ«n J. Do clinical assessments, steady-state or daily-life gait characteristics predict falls in ambulatory chronic stroke survivors? J Rehabil Med. 2017;49:402–9. 41. van Schooten KS, Pijnappels M, Rispens SM, Elders PJM, Lips P, Daffertshofer A, et al. Daily-Life Gait Quality as Predictor of Falls in Older People: A 1-Year Prospective Cohort Study. Glasauer S. PLoS One. 2016 Jul 7;11:e0158623. 42. Rispens SM, Van Dieën JH, Van Schooten KS, Cofré Lizama LE, Daffertshofer A, Beek PJ, et al. Fall-related gait characteristics on the treadmill and in daily life. J Neuroeng Rehabil. 2016 Feb 2;13:12. 43. Storm FA, Nair KPS, Clarke AJ, Van der Meulen JM, Mazzà C. Free-living and laboratory gait characteristics in patients with multiple sclerosis. PLoS One. 2018;13:e0196463. 44. Kirschberg J, Goralski S, Layher F, Sander K, Matziolis G. Normalized gait analysis parameters are closely related to patient-reported outcome measures after total knee arthroplasty. Arch Orthop Trauma Surg. 2018 May 2;138:711–7. 45. Jones GG, Kotti M, Wiik A V, Collins R, Brevadt MJ, Strachan RK, et al. Gait comparison of unicompartmental and total knee arthroplasties with healthy controls. Bone Joint J. 2016 Oct;98-B:16–21. 46. McClelland JA, Feller JA, Webster KE. Sex Differences in Gait After Total Knee Arthroplasty. J Arthroplasty. 2018 Mar;33:897–902. 47. Kluge F, Hannink J, Pasluosta C, Klucken J, Gaßner H, Gelse K, et al. Pre-operative sensor-based gait parameters predict functional outcome after total knee arthroplasty. Gait Posture. 2018 Oct;66:194–200. 48. Hardt S, Schulz MRG, Pfitzner T, Wassilew G, Horstmann H, Liodakis E, et al. Improved early outcome after TKA through an app-based active muscle training programme—a randomizedcontrolled trial. Knee Surgery, Sport Traumatol Arthrosc. 2018 Nov 27;26:3429–37.

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Het doel van de studies beschreven in dit proefschrift was het evalueren van verschillende innovaties gericht op het verbeteren van functionele uitkomsten en functionele uitkomstmaten van knievervangende operaties waarbij een totale knieprothese (TKP) wordt geplaatst. In deel 1 wordt het effect van een zogenaamd fast-track protocol op klinische en functionele uitkomsten van een TKP operatie bestudeerd. Verder werden aanpassingen aan het ontwerp van de articulatie op de functionele uitkomst van patiënten met een TKP geëvalueerd middels een prospectieve gerandomiseerde studie en een uitgebreid literatuur overzicht. In deel 2 wordt een vragenlijst, gericht op actievere patiënten, gevalideerd in het Nederlands. Verder worden in dit deel studies beschreven waarbij geïnstrumen teerde loopanalyses met accelerometers zijn uitgevoerd in zowel een klinische- als thuissituatie. Hierbij werd beoordeeld of deze analyses een toegevoegde waarde hebben bij het analyseren van functionele uitkomsten van patiënten met een TKP ten opzichte van het gebruik van vragenlijsten die door patiënten zelf worden ingevuld (patient reported outcome measures, PROMs).

DEEL 1 Verbeteren van functionele uitkomst Fast-track protocol Het introduceren van ziekenhuisbrede fast-track protocollen voor TKP patiënten heeft gezorgd voor sneller mobiliseren en ontslag van deze patiënten uit het ziekenhuis, terwijl pijn en het gebruik van pijnstillers verminderen zonder een toename in complicaties of heropnames. In de jaren ‘90 was een ziekenhuisopname van minder dan een week na een TKP operatie een uitzondering, maar fast-track protocollen hebben in het begin van het millennium de opnameduur verkort naar drie tot vijf dagen. Hierna zijn deze protocollen doorontwikkeld om de opnameduur verder te verkorten en patiënten sneller te mobiliseren na hun operatie. Studies die deze protocollen analyseerden, richtten zich meestal op klinische uitkomsten op de midden tot lange termijn. Hierbij werden de eerste metingen vaak pas twee tot zes weken na de operatie verricht. Dit is tegenstrijdig met de doel van de interventies waaruit een fast-track protocol vaak bestaat, namelijk pijnvermindering en het starten van de revalidatie in de eerste uren tot dagen na de operatie. Daarom is in Hoofdstuk 2 een gerandomiseerde klinische trial (RCT) uitgevoerd waarin een fast-track protocol, gericht op ontslag twee dagen na een TKP operatie, is geëvalueerd. Hierbij is specifiek gekeken naar de eerste zeven dagen na de operatie en zijn zowel klinische als functionele uitkomstmaten gebruikt. Vijftig patiënten zijn random verdeeld in twee groepen

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en tot vijf jaar na de operatie gevolgd. Patiënten die het fast-track protocol hadden ondergaan, hadden significant lagere pijnscores direct na en in de eerste uren na de operatie in vergelijking met patiënten die het reguliere protocol hebben gevolgd. Ook bleven de pijnscores significant lager in deze groep gedurende de hele eerste week na de operatie. In de eerste week zijn ook significant betere scores gezien in de fast-track protocol groep bij verschillende functionele testen. Er zijn echter slechts een paar significante verschillen tussen de groepen gevonden na twee, zes en twaalf weken en één, twee en vijf jaar na de operatie. Dit is een indicatie dat ontslag uit het ziekenhuis na twee dagen bij de meeste patiënten na een TKP operatie haalbaar is en dat de belangrijkste winst van een fast-track protocol wat betreft klinisch en functionele uitkomsten behaald wordt in de eerste zeven dagen, zonder dat dit een nadelig effect heeft op de lange termijn. Onderzoek naar functionele uitkomsten van fast-track protocollen zou zich dan ook meer moeten richten op deze vroege tijdsperiode. Prothese ontwerp Verschillende (veronderstelde) beperkingen van de zogenaamde fixed bearing TKP (FB-TKP) in het nabootsen van de drie-dimensionale kinematica van de natieve knie hebben geleid tot het ontwikkelen van mobile bearing TKP (MB-TKP) in de jaren ‘80 van de vorige eeuw. Doordat de polyethyleen (PE) insert van de MB-TKP kan bewegen ten opzichte van de tibiacomponent, werd verondersteld dat MB-TKP een aantal voordelen heeft ten opzichte van FB-TKP: minder slijtage van de insert, minder tekenen van loslating, een langere overlevingsduur van de prothese en betere klinische uitkomsten. Er zijn in de jaren daarna vele studies uitgevoerd waarin verschillende uitkomsten van MB-TKP en FB-TKP operaties zijn onderzocht. Systematische reviews en meta-analyses op dit onderwerp hebben tot nu toe geen significante verschillen kunnen aantonen tussen beide ontwerpen. Deze systematische literatuurstudies en meta-analyses gebruiken echter vaak dezelfde RCTs, waarvan maar een beperkt aantal gedaan zijn. Deze typen onderzoek nemen studies met een lager “level of evidence” (methodologische kwaliteit) niet mee, ondanks dat deze studies mogelijk toegevoegde waarde hebben in de discussie over welk type bearing de voorkeur verdient. Zo is het bijvoorbeeld interessant hoeveel slijtage een insert heeft nadat deze verwijderd is uit de knie van een patiënt, echter wordt dit soort informatie alleen beschreven in cohort studies. In Hoofdstuk 3 wordt daarom een uitgebreid overzicht van de beschikbare literatuur gegeven waarin alle studies die MB-TKP en FB-TKP vergelijken zijn meegenomen, ongeacht methodologische opzet. Na het analyseren van 127 artikelen (9 meta-analyses, 3 systematische literatuur studies,

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48 RCT‘s, 44 vergelijkende studies, 10 niet systematische literatuur studies en 13 intern vergelijkende studies die patiënten onderzochten met een bilaterale TKP (één MB-TKP en één FB-TKP)), moet geconcludeerd worden dat nog steeds maar een beperkt aantal artikelen kleine verschillen rapporteert tussen de twee typen bearing. Een voorkeur voor een bepaald type bearing moet derhalve afhangen van andere factoren, zoals de ervaring van een orthopeadisch chirurg met een bepaald type prothese. De ontwerpen van de PE inserts van zowel MB-TKP als FB-TKP protheses zijn in de loop van de jaren verder ontwikkeld, waarbij fabrikanten en onderzoekers hoopten dat deze nieuwe ontwerpen zouden zorgen voor betere klinische en functionele uitkomsten voor patiënten. In Hoofdstuk 4 zijn vier verschillende typen inserts onderzocht: twee typen mobile bearing (roterend en roterend/translerend) en twee typen fixed bearing (normaal en verdiept) van één merk prothese. De studie bestond uit analyses van overleving van de prothese, kwaliteit van leven van de patiënt, en klinische en functionele uitkomsten. Van de 237 patiënten die in twee ziekenhuizen zijn geïncludeerd, hebben 146 patiënten het gehele protocol doorlopen. Er zijn geen verschillen gevonden in de functionele uitkomstmaten en de kwaliteit van leven tussen de verschillende groepen patiënten met de verschillende typen TKP. Er is een klein significant verschil gevonden in de Knee Society Score tussen de twee typen mobile bearing over de tijd, wat echter als niet klinisch relevant beschouwd kan worden. De overleving van de MB-TKP was significant slechter vergeleken met FB-TKA na vijf jaar (respectievelijk 94.7% en 99.2%). ‘Tijd tot revisie’ (ongeacht welke reden) was ook significant beter in de FB-TKP groep. Wanneer deze uitkomsten werden uitgesplitst naar specifieke typen inserts werd geen verschil meer gevonden, alhoewel er wel aanwijzingen waren dat de roterende/translerende mobile bearing insert het slechtst presteerde van de vier types insert die onderzocht zijn. Van dit specifieke merk prothese verdient derhalve de FB-TKP de voorkeur.

DEEL 2 Verbeteren van functionele uitkomstmaten Patient Reported Outcome Measures Verreweg de meest gebruikte manier om klinische uitkomsten van TKP operaties te kwantificeren is door patiënten te vragen om vragenlijsten in te vullen, bekend onder de Engelse term PROMs. Dit is een makkelijke manier om data te verzamelen over o.a. patiënttevredenheid, ervaren pijn en kwaliteit van leven. De meeste van deze vragenlijsten worden al decennia lang gebruikt. Recente analyses

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van de klinimetrische eigenschappen van PROMs laten echter zien dat er vaak sprake is van een vloer- of plafondeffect bij het evalueren van uitkomsten van TKP operaties, waarbij een relatief groot percentage van de respondenten respectievelijk de minimale of maximale score behaalt. Een mogelijke reden hiervoor is dat de populatie van patiënten met een TKP de laatste jaren is veranderd, waarbij patiënten steeds actiever blijven of jonger zijn als ze de operatie ondergaan. Actievere patiënten scoren sneller hoge scores op PROMs. Om onderzoekers een mogelijkheid te bieden om onderscheid te kunnen maken tussen de ‘actieve’ en ‘zeer actieve’ patiënt met een TKP hebben Talbot en collega’s de “High Activity Arthroplasty Score” (HAAS) ontwikkeld, welke reeds in het Engels en het Frans gevalideerd is. Hoofdstuk 5 bevat een vertaling en validatie van de HAAS naar het Nederlands. De HAAS en enkele andere PROMs zijn ingevuld door 108 patiënten, waarvan 51 patiënten na een totale heupprothese operatie en 57 patiënten na een TKP operatie. De Nederlandse versie van de HAAS liet een goede interne consistentie zien en had significante positieve correlaties met vrijwel alle andere PROMs. Relevant hierbij is dat de HAAS noch een vloer effect, noch een plafond effect laat zien. Loopanalyse Accelerometers worden al jaren met succes gebruikt voor het analyseren van bewegingen zoals lopen en de effecten van verschillende ziektes en aandoeningen op het lopen. Deze apparaten worden tegenwoordig vaker gebruikt binnen de orthopedie omdat ze steeds kleiner en makkelijker beschikbaar worden. Daarnaast is er steeds meer evidence dat accelerometers een gevalideerde manier zijn om kwaliteit en kwantiteit van lopen te analyseren. Om te bepalen of accelerometers gebruikt kunnen worden voor het analyseren van functionele uitkomsten van TKP patiënten zijn in Hoofdstuk 6 accelerometers gebruikt om de loopkwaliteit van 65 patiënten te meten vóór en één jaar na een unilaterale TKP operatie. Deze accelerometers, geplaatst op de lage rug, meten versnelling in drie dimensies: anterieur-posterieur (AP), mediolateraal (ML), en verticaal (VT). De loopmetingen bestonden uit het lopen van twee keer 50 meter tijdens het bezoek van de patient aan de polikliniek. Daarnaast is aan hen gevraagd om verschillende PROMs in te vullen. Een factoranalyse is verricht om die loopparameters te identificeren die het meest representatief waren voor loopkwaliteit. Er zijn met de factoranalyse drie factoren geïdentificeerd voor kwaliteit van lopen: ‘AP/VT loop kwaliteit‘, ‘ML loop kwaliteit’ en ‘Symmetrie’. Alle PROMs zijn in de factoranalyse in een aparte factor gegroepeerd, los van de loopkwaliteit parameters, wat impliceerde dat de geïnstrumenteerde loopkwaliteit parameters andere aspecten van functionele

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uitkomst meten dan de PROMs. De correlaties tussen de waarden van de loopparameters en de PROM parameters zijn berekend tussen de beide meetmomenten, waarbij slechts matige associaties zijn gevonden. Dit bevestigt de premisse dat PROMs en geïnstrumenteerde loopkwaliteit metingen andere aspecten van functionele uitkomst na een TKP operatie meten en dat accelerometer metingen derhalve een toegevoegde waarde hebben bij het evalueren van de loopfunctie van patiënten met een TKP. Voortbordurend op de kennis vergaard in Hoofdstuk 6, is in Hoofdstuk 7 onderzocht welke resultaten een analyse met een accelerometer van loopparameters van TKP patiënten in hun thuissituatie zou laten zien. In deze studie hebben 38 patiënten gedurende een hele week een accelerometer dag en nacht gedragen, vóór en drie maanden na het vervangen van hun knie. Wederom is patiënten gevraagd om naast het dragen van de accelerometer PROMs in te vullen. Op beide meetmomenten is data verzameld over kwaliteit van lopen, loopgedrag (hoeveelheid en snelheid van lopen) en de perceptie van patiënten over hun eigen loopcapaciteiten. Er werd na drie maanden geen significante verbetering gevonden in zowel kwaliteit van lopen als loopgedrag. Hier stond tegenover dat de eigen perceptie van patiënten over hun capaciteiten wat betreft lopen en de PROMs scores wel significante verbeteringen liet zien na drie maanden. Deze discrepantie toont aan dat de perceptie van patiënten over hun loopcapaciteiten niet per se representatief is voor hun dagelijkse functie en activiteiten. Het lijkt derhalve dat naast PROMs ook metingen met een accelerometer nodig zijn om te meten welk niveau van functionele uitkomst patiënten thuis behalen na een TKP operatie. Het meten van functionele uitkomsten na een TKP operatie met accelerometers in de thuissituatie van patiënten kan aanvullende informatie opleveren voor orthopedisch chirurgen en andere behandelaars, en kan in de toekomst wellicht ook gebruikt worden om revalidatieschema’s voor individuele patiënten te ontwikkelen.

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CHAPTER 10 Dankwoord

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Dit proefschrift had nooit het daglicht gezien zonder de hulp, tijd en goede adviezen van een groot aantal mensen. Hieronder wil ik zoveel mogelijk van hen bedanken, maar het kan bijna niet anders dan dat ik een paar mensen vergeet. Allereerst mijn promotor, professor van Dieën. Beste Jaap, dank dat je als bewegingswetenschapper mij als medicus onder je hoede hebt willen nemen. Ik blijf me erover verbazen dat ongeacht het tijdstip of de dag van de week dat ik via de mail iets opstuurde naar jullie, jij steevast als eerste terug mailde. Je had altijd een heldere visie en een duidelijke mening. Mede daardoor heb jij ervoor gezorgd dat ik op schema bleef en dat ik dit proefschrift op tijd hebben kunnen afronden. Beste Marco. Zonder de vele overlegmomenten met jou gedurende de afgelopen jaren was dit proefschrift er nu (nog) niet geweest. Onder het genot van een kop koffie hadden we het vaker niet over onderzoek dan wel, maar ik had na iedere sessie weer frisse moed en een fikse lijst met to-do punten. Ik vind het bewonderenswaardig hoe jij perfect weet te laveren tussen de academische wereld van de bewegingswetenschappers en de klinische realiteit van patiëntgebonden onderzoek in het ziekenhuis. Ik hoop dat ik ook nu dit proefschrift af is nog langs mag komen om bij te kletsen. Ik zorg voor de koffie. Beste Bart. Dankzij jouw drive en eindeloze inzet blijft het orthopaedische onderzoek vanuit Alkmaar en CORAL floreren en daardoor heb ik de mogelijkheid gekregen om dit onderzoek grotendeels tegelijk met mijn opleiding te doen. Of het nu te maken had met je rol als co-promotor of met je rol als opleider, ik kon altijd bij je terecht met vragen of problemen. Ik ben blij dat je me hebt aangestoken met je enthousiasme voor de combinatie van bewegingswetenschappen en orthopaedie. De leden van de lees- en promotiecommissie: dr. Keijser, dr. Meijer, professor Nelissen, professor Pijnappels, professor Verhaar. Dank dat jullie de tijd en moeite hebben genomen om mijn proefschrift te beoordelen. Ik kijk ernaar uit om met u allen van gedachten te wisselen. De collega’s van CORAL: Karin, Kirsten, Jacintha, Karin, Marleen, Ise, Pieter en alle andere assistenten die er in al die jaren gezeten hebben. Tijdens het jaar in het CORAL kantoor en de tijd erna had ik altijd een plek om naartoe te gaan waar ik naast veel werk ook nog veel gezelligheid kon vinden. In de jaren dat ik in een

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ander ziekenhuis werkte was jullie hulp met alle praktische zaken, enveloppen sturen, metingen doen etc. onmisbaar, waarvoor ik jullie niet genoeg kan bedanken. Een aantal mensen bij de afdeling bewegingswetenschappen van de VU hebben mij als vaak onwetend medicus geholpen om wegwijs te worden in de wereld van loopanalyses. Roel, Mirjam en Michiel, zonder jullie geduldige uitleg had ik deze materie waarschijnlijk nooit kunnen begrijpen. Mijn collega AIOS van de ROGO Noord-West. Jullie zorgen ervoor dat ik iedere dag weer met plezier naar mijn werk ga. Ook als ik weer eens wilde sparren over onderzoek of als ik een mindere dag had was er altijd een luisterend oor. Ik vind het mooi om te zien hoe we ondanks alle onrust in de ROGO de laatste jaren een hecht team zijn gebleven. Emiel, Emile, Guus, Hanneke, Manon, Ranhilde, Simon, Steven en aanhang. Wat begon als een groepje mountainbikers is een geweldige vriendengroep geworden. Zelfs nadat ik naar Utrecht ben verhuisd blijven de fietstochten, oudejaarsavonden, klusdagen, weekendjes weg, whiskyproeverijen en kookavonden gewoon doorgaan en ik zou ze voor geen goud willen missen. Beste VWO vriendengroep die ik niet van het VWO ken. Dank dat jullie mij als koude kant opgenomen hebben in jullie groep van Tukkers en Achterhoekse boeren. Dit is zo uit de hand gelopen dat ik zelfs jullie toch soms wat obscure Herman Finkers referenties begin te herkennen. Jasper, Koen, Peter en Tijn: de poker- en muziekavonden met uitgebreide discussies over vanalles en nogwat zijn voor mij iedere keer weer een hoogtepunt. Laten we proberen deze ondanks alle drukke levens wel regelmatig te blijven organiseren! Iedereen die wel genoemd dient te worden maar die ik niet onder een ander lijstje kan scharen: Anco, Bas, Jaap, Laurens, Maarten, Maaike. Ook jullie hebben allemaal op jullie eigen manier een onmisbare bijdrage aan mijn proefschrift geleverd. Tijn en Navin, heel veel dank dat jullie mij als paranimf willen ondersteunen tijdens mijn verdediging. Ik hoop dat ik jullie niet te veel werk bezorgd heb. Ik ga er vanuit dat we straks samen terugkijken op een prachtige dag!

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Mijn schoonfamilie: Gudie, JosĂŠ, Debbie, Jeroen, Anne en Robert. Dank jullie wel dat jullie mij in de familie hebben opgenomen. Ondanks de Twentse tongval voel ik mij bij jullie altijd thuis. Lieve Ilona. Als klein zusje ben je altijd geĂŻnteresseerd gebleven in waar ik nu weer mee bezig was, ondanks dat het ver van jouw eigen vakgebied af staat. Ik hoop dat Jorit, Sander, Yara en wij nog veel mooie herinneringen samen mogen maken in de toekomst. Lieve pap en mam. Ik ben er trots op dat jullie mijn ouders zijn en ik ben heel blij met alle raad en daad die jullie door de jaren heen hebben gegeven. Ik weet dat ik met alle drukte met werk, onderzoek en gezinsleven ik niet zo vaak bel of langskom als jullie wellicht zouden willen. Nu er kleinkinderen in het spel zijn gekomen zien we elkaar gelukkig weer vaker, en ik ga er vanuit dat dat nog lang zo gaat blijven! Lieve Maud, ook een woordje voor jou terwijl je er nog niets van begrijpt. Ik ben heel blij dat jij ons leven bent binnen gekomen tijdens mijn promotie. Vanaf nu wordt mijn onderzoeksdag een papadag. Allerliefste Manon. In het dankwoord van je eigen proefschrift schreef je dat je hoopte dat je net zoveel aan mijn promotie kon bijdragen als ik bij jou. Wat mij betreft heb je veel meer gedaan dan dat. Een eigen huis-epidemioloog is van onschatbare waarde, maar vooral je eindeloze interesse, geduld en liefde hebben heel veel voor me betekend. Dank dat je begrip kon opbrengen als ik weer eens een avond achter de computer ging zitten in plaats van dingen samen te doen. Ik hoop dat we nu meer tijd hebben om met zijn allen te genieten.

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Bas was born on 27 October 1987 in Alphen aan den Rijn. In 2005 he graduated from the Stedelijk Gymnasium Nijmegen and started studying Medicine at the Radboud University in Nijmegen. During his study, he participated in several boards and committees, including one year fulltime at the Nijmegen Student Sports Association (NSSR) and a year as an elected member of the University Student Council. He also spent six months in Vancouver, Canada for a research internship at the lab of professor Tetzlaff at the International Collaboration On Repair Discoveries (ICORD), where his interest and enthusiasm for scientific research grew. During his master he discovered a passion for orthopaedic surgery. Combining his interests he started working at the Centre for Orthopaedic Research in Alkmaar (CORAL) in 2013 studying patients with knee osteoarthritis. This evolved into a PhD candidacy in cooperation with the department of Behavioural and Movement Sciences of the Vrije Universiteit Amsterdam. In 2014 he started his orthopaedic residency training at the general surgery department of the VU medical centre (prof. dr. D.L. van der Peet), followed by residency training at the orthopaedic departments of the Spaarne Gasthuis (Dr. A van Noort), VU medical centre (Dr. J.A. van der Sluijs), and Noordwest Ziekenhuisgroep Alkmaar (Dr. B.J. Burger). He is expected to finish his residency in 2021. Bas lives together with his wife Manon and daughter Maud (2019) in Utrecht.

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CHAPTER 12 Publication list

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Gait quality assessed by trunk accelerometry after total knee arthroplasty and its association with patient related outcome measures BL Fransen, N Mathijssen, K Slot, N De Esch, H Verburg, OPP Temmerman, MJM Hoozemans, JH van Dieën. Accepted for publication in Clinical Biomechanics. Fast-track total knee arthroplasty improves clinical and functional outcome in the first seven days after surgery. A randomized controlled pilot study with five years follow-up. BL Fransen, MJM Hoozemans, KD Argelo, LCM Keijser, BJ Burger. Archives of Orthopedic and Trauma Surgery. 2018;138(9):1305-1316. Cross-cultural adaptation and validation of the Dutch version of the High Activity Arthroplasty Score BL Fransen, HJ Kan, J Posthuma de Boer, MJM Hoozemans, BJ Burger. Nederlands Tijdschrijft voor Orthopedie. 2018;25(3):68-74. No differences between fixed- and mobile-bearing total knee arthroplasty. BL Fransen, DC van Duijvenbode, MJM Hoozemans, BJ Burger. Knee Surgery, Sports Traumatology, Arthroscopy. 2017;25(6):1757-1777. Predictive Factors for Functional Outcome after Conservative Treatment of Midshaft Clavicular Fractures: A Retrospective Cohort Study NP Hockers, RJ Hillen, BL Fransen, JIP Willems, Marco JM Hoozemans, BJ Burger. Clinical Research in Orthopedics. 2017;1:1-4. Pre-hospital and Acute Management of Traumatic Spinal Cord Injury in the Netherlands: Survey Results Urge the Need for Standardization BL Fransen, AJ Hosman, JJ van Middendorp, M Edwards, PM van Grunsven, H van de Meent. Spinal Cord. 2016;54(1):34-38. In Reply: “Does Insert Type Affect Clinical and Functional Outcome in Total Knee Arthroplasty?”. BL Fransen, MJM Hoozemans, LCM Keijser, ME van Lent, CCPM Verheyen, BJ Burger. The Journal of Arthroplasty. 2016;31(7):1615-1616.

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PUBLICATION LIST

Direct Anterior Approach versus Posterolateral Approach in Total Hip Arthroplasty: One Surgeon, Two Approaches BL Fransen, MJM Hoozemans, CJ Vos. Acta Orthopaedica Belgica. 2016;82(2):240-248. Does Insert Type Affect Clinical and Functional Outcome in Total Knee Arthroplasty? A Randomised Controlled Clinical Trial With 5-Year Follow-Up. BL Fransen, MJM Hoozemans, LCM Keijser, ME van Lent, CCPM Verheyen, BJ Burger. The Journal of Arthroplasty. 2015;30(11):1931-1937. Operative resection is a viable treatment of macrodactyly of the foot caused by lipofibromatous hamartoma; A case study with 5 year follow-up. BL Fransen, MGJ Broeders, FJT van Oosterom, NDB Gilhuijs, BJ Burger. Foot and Ankle Surgery. 2014;20(3):e47-e50. Recommendations for diagnosis and treatment of spondylodiscitis BL Fransen, E de Visser, A Lenting, G Rodenburg, AA van Zwet, EH Gisolf. The Netherlands Journal of Medicine. 2014;72(3):135-138. Ketogenic diet improves forelimb motor function after spinal cord injury in rodents. F Streijger, WT Plunet, JH Lee, J Liu, CK Lam, S Park, BJ Hilton, BL Fransen, KA Matheson, P Assinck, BK Kwon, W Tetzlaff. PLoS One. 2013;8(11):e78765. 12-jarige jongen met een elleboogluxatie en uitval van de nervus ulnaris BL Fransen, JS Luttjeboer, CJM van Loon. Nederlands Tijdschrift voor Traumatologie. 2013;6:169.

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